Blueprint of Pediatric Endocrinology Book

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Blueprint in Pediatric Endocrinology

Abdulmoein Eid Al-Agha, MBBS, DCH, FRCPCH Pediatric Endocrinologist King AbdulAziz University Faculty of Medicine Jeddah, Saudi Arabia

1st Edition: 1435 A.H. (2014 A.D.)

Table of Contents

Chapter 1: Basic Endocrinology Introduction…………………………………………………………………….. 3 Effects of hormones…………………………………………………………….. 3 Types of hormones……………………………………………………………… 4 Types of Hormone Receptors………………...………………………………... 5 Loss – of – function mutations………………………………………………….. 7 Gain – of – function mutations……………………………...………………….. 9 Fetal Brain Programming ………………………………………………………. 10 The endocrine system ……………………………...…………………………... 10 Hypothalamic-Pituitary Relationships………………………………………….. 10 Hypothalamic Controls…………………………………………………………. 11 Anterior Pituitary Function……………………………………………………... 11 Posterior Pituitary Function…………………………………………………….. 13 Chapter 2: Disorders of Calcium and Bone Metabolism Introduction…………………………………………………………..…………. 17 Vitamin D ………………………………………………………………………. 18 Parathyroid glands…………………………………………………...…………. 19 Calcitonin……………………………………………………………………….. 20 The calcium-sensing receptor (CaSR)………………………………………….. 21 Parathyroid Hormone–Related Peptide (PTHrP)……………………………….. 21 Hypocalcaemia………………………………………………………………….. 22 Hypocalcaemia in neonates……………………………………………………... 22 Hypocalcaemia in infants & children…………………………...……………… 23 Clinical manifestations of Hypocalcaemia…………………...………………… 24 Investigations of Hypocalcaemia……………………………………………….. 25 Rickets and Osteomalacia………………………………………………………. 28 Causes of Rickets ………………………………………………………………. 29 Vitamin D–dependent rickets (type I)…………………………………………... 35

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Vitamin D-resistant rickets (type II vitamin D–dependent rickets) ……………. 35 Hypophosphatemic Rickets…………………………………………………….. 37 Hypophosphatasia ……………………………………………………………… 37 Treatment of Hypophosphatasia ……………………………………………….. 38 Drug-induced rickets……………………………………………………………. 39 Fanconi's syndrome …………………………………………………………….. 40 McCune-Albright syndrome……………………………………………………. 40 Renal Osteodystrophy (Renal Rickets)…………………………………………. 41 Hepatic Rickets…………………………………………………………………. 41 Malabsorption & Rickets……………………………………………………….. 41 Oncogenic Osteomalacia……………………………………………………….. 42 Hypoparathyroidism……………………………………………………………. 43 Pseudohypoparathyroidism (PHP)……………………………………………… 49 Pseudopseudohypoparathyroidism …………………………………………….. 51 Treatment of Pseudopseudohypoparathyroidism ………………………………. 54 Hypomagnesaemia……………………………………………………………… 54 Hypercalcemia in children……………………………………………………… 55 Oncogenic Hypercalcemia……………………………………………………… 59 Clinical manifestations of hypercalcemia………………………………………. 59 Treatment of Oncogenic Hypercalcemia……………………………………….. 60 Osteoporosis in children and adolescence……………………………………… 63 Primary osteoporosis……………………………………………………………. 64 Osteogenesis imperfecta (OI)…………………………………………………... 65 Idiopathic juvenile osteoporosis ……………………………………………...... 67 Secondary osteoporosis…………………………………………………………. 67 Chapter 3: Disorders of sex development Classification of disorders of sexual development……………………….....…… 80 Stages of sexual differentiation…………………………………………………. 80 Sex differentiation in embryo and fetus………………………………………… 80 Gonadal differentiation…………………………………………………………. 81 Causes of abnormal sexual differentiation……………………………………… 85 Table of Contents vii

Congenital Adrenal hyperplasia (CAH)………………………………………… 85 Maternal androgens …………………………………………………………….. 89 Aromatase enzyme deficiency………………………………………………….. 89 XX Male Syndrome ……………………………………………………………. 90 Persistent Müllerian Duct Syndrome (PMDS)……………….………………… 90 Gonadotrophin deficiency causing DSD……………………………………….. 91 Leydig cell agenesis ………………………………………………….………… 91 Testosterone biosynthesis defects………………………………………………. 91 Androgen Insensitivity Syndrome (AIS) ………………………….…………… 92 5-alpha-reductase type 2 deficiency ……………………………….…………… 93 Ovotesticular disorders of sexual development (formerly true hermaphroditism) 93 …………………………………………………………… Partial gonadal dysgenesis……………………………………………………… 94 Pure gonadal dysgenesis………………………………………………………... 95 XY Female Syndrome …………………………………………………………. 95 Diagnosis of CAH……………………………………………………….……… 96 Medical management of CAH………………………………………………...... 98 Considerations for sex assignment in CAH………………...…………………... 99 Dysmorphic syndromes with DSD……………………………………………... 101 Micropenis……………………………………………………………………… 105 Hypospadias ……………………………………………………………………. 110 Cryptorchidism………………………………………………………………..... 110 Retractile testicle(s)…………………………………………………………….. 114 Chapter 4: Reproductive Disorders Normal pubertal development………………………………………..………… 117 Physiology of Puberty……………………………...…………………………… 118 Puberty onset…………………………………………………...……………….. 121 Physical changes in boys during Puberty……………………………………...... 122 Physical changes in girls during pubrty………………………………………… 124 Precocious Puberty……………………………………………………………… 126 Sequelae of precocious puberty………………………………………………… 127 Causes of central (GnRH dependent)…………………………………………... 128 viii Blueprint in Pediatric Endocrinology

Environmental & genetic factors influencing HPG axis activation………..…... 128 Peripheral precocious puberty…………………………………...……………… 129 McCune-Albright Syndrome (MAS)………………………………...…………. 131 Variation of normal pubertal development…………………………...………… 133 Premature pubarche ………………………………………………...………….. 134 Premature Thelarche ………………………………………………...…………. 134 Growth hormone (GH)………………………………………………...………... 137 Cyproterone acetate (Androcur)………………………………………..………. 139 Medroxyprogestrone acetate (Depo-Provera)…………………………...……… 140 GnRH antagonist…………………………………………………………...…… 140 Treatment of peripheral precocious puberty………………………………...….. 142 Complications of peripheral precocious puberty……………………………...... 145 Delayed puberty………………………………………………………………… 145 Hypogonadotropic hypogonadism……………………………………………… 146 Constitutional Delay of Growth and Puberty (CDGP)…………………………. 149 Hypothalamic-pituitary disorders………………………………………………. 149 Hypergonadotrophic hypogonadism……………………………………………. 150 Turner's syndrome ……………………………………………………………… 151 Klinefelter's syndrome …………………………………………………………. 152 Pubertal induction………………………………………………………………. 155 Polycystic Ovarian Syndrome (PCOS)…………………………………………. 156 Hirsutism……………………………………………………………………….. 160 Ferriman-Gallwey score for hirsutism…………………………………...…….. 161 Gynecomastia…………………………………………………………………… 165 Causes of elevated estrogen levels or activity………………………………….. 167 Causes of testosterone deficiency………………………………………………. 167 Causes of impaired testosterone action…………………………………………. 168 Chapter 5: Thyroid disorders in children The Thyroid Gland……………………………………………………………… 173 The Placenta and the Thyroid Gland…………………………………………… 174 Physiology the Thyroid Gland………………………………………………..... 175 Table of Contents ix

Thyroid hormone synthesis…………………………………………………….. 176 Congenital Hypothyroidism (CH)……………………………………………… 177 Causes of permanent congenital hypothyroidism ……………………………… 178 Diagnostic tests in thyroiditis…………………………………………………… 178 Treatment of thyroiditis………………………………………………………… 186 Drugs or goitrogens…………………………………………………………….. 187 Secondary or tertiary hypothyroidism………………………………………….. 187 Thyroid hormone resistance…………………………………………………..... 187 Clinical manifestations of acquired hypothyroidism…………………………… 188 Average daily doses of L-Thyroxin…………………………………………..... 190 Hyperthyroidism……………………………………………………………….. 190 Transient neonatal hyperthyroidism……………………………………………. 190 Clinical manifestations of hyperthyroidism…………………………………..... 191 Neonatal thyrotoxicosis………………………………………………………… 192 Permanent neonatal hyperthyroidism…………………………………………… 193 Chapter 6: Growth and Growth Disorders Hormonal influences on fetal growth ………………………..………………… 209 Factors determining normal growth depend on the child's age………………… 209 Growth assessment……………………………………………………………… 210 Short stature…………………………………………………………………...... 212 Causes of short stature………………………………………………………...... 213 SHOX deficiency syndromes …………………………………………………... 218 Malnutrition…………………………………………………………………….. 220 Malabsorption / Gastrointestinal Diseases……………………………………… 220 Syndromes associated with short stature……………………………………….. 221 Congenital GH deficiency………………………………………………………. 229 Hypothalamic–Pituitary Malformations………………………………………... 229 Hereditary GH Deficiency……………………………………………………… 230 GH1 gene……………………………………………………………………...... 231 GHRH Receptor………………………………………………………………… 231 Congenital structural CNS defects …………………………………………….. 231 x Blueprint in Pediatric Endocrinology

CNS Tumors …………………………………………………………………… 232 Craniopharnygioma …………………………………………………………...... 232 Cranial irradiation ……………………………………………………………… 233 Growth velocity………………………………………………………………… 236 Laboratory evaluation of short stature………………………………………...... 238 Subsequent tests depend on the diagnosis and may include……………………. 238 GH stimulation tests…………………………………………………………...... 239 Serum markers of GH secretion………………………………………………… 240 Indications of GH testing in children…………………………………………… 241 Complications and adverse effects of rhGH treatment…………………………. 244 Monitoring GH therapy…………………………………………………………. 245 Defining the Response to GH Treatment……………………………………...... 245 The Role of GH Treatment Alternatives………………………………………... 246 Anabolic steroids……………………………………………………………….. 246 IGF-1………………………………………………………………….……….... 246 GnRH analogs (GnRHa)………………………………………………………... 247 Aromatase inhibitors (AIs)……………………………………………………... 247 Psychological counseling……………………………………………………...... 248 Growth hormone insensitivity ………………………………………………...... 248 Post-receptor forms of GH insensitivity………………………………………... 249 IGF-1 gene abnormalities ……………………………………………………… 250 IGF-binding protein abnormalities …………………………………………….. 250 IGF-1 receptor gene abnormalities …………………………………………….. 250 Diagnosis of Primary Insulin-Like Growth Factor-1 Deficiency ……………… 250 Overgrowth in the fetuses ……………………………………………………… 251 Soto's syndrome (cerebral gigantism) ………………………………………….. 252 Tall stature ……………………………………………………………………... 253 Chapter 7: The Pituitary Gland Inroduction…...…………………………………………………………………... 261 Hypopituitarism………………………………………………………………… 267 Genetic forms of pituitary hormone deficiency………………………………… 268 Table of Contents xi

Hypopituitarism in neonates……………………………………………………. 271 Hypopituitarism in older infants and children………………………………...... 272 Congenital hypopituitarism…………………………………………………….. 272 Growth hormone deficiency…………………………………………………..... 274 Acquired hypopituitarism……………………………………………………..... 275 Diagnosis of hypopituitarism…………………………………………………… 276 Corticotrophin deficiency………………………………………………………. 276 Insulin-induced Hypoglycemia Test …………………………………………… 276 Synacthen (Cosyntropin) stimulation test………………………………………. 276 Thyrotropin deficiency………………………………………………………..... 277 Gonadotropin deficiency……………………………………………………….. 277 Growth hormone deficiency…………………………………………………..... 277 Adrenocorticotropic hormone deficiency ……………………………………… 278 Thyroid-stimulating hormone deficiency ……………………………………… 279 Luteinizing hormone and follicle-stimulating hormone deficiency…………..... 279 Physiology of water balance …………………………………………………… 280 Approach to the patient with polyuria, polydipsia, and hypernatremia ……….. 281 Central diabetes insipidus ……………………………………………………… 282 Nephrogenic diabetes insipidus (NDI)…………………………………………. 283 Treatment of central diabetes insipidus ……………………………………….. 284 Treatment of nephrogenic diabetes insipidus ………………………………….. 286 Suggested doses of Desmopressin……………………………………………… 287 Water deprivation test interpretation …………………………………………... 288 The syndrome of inappropriate Antidiuretic hormone (SIADH)……………..... 288 Hypodipsia ……………………………………………………………………... 288 Acute hyponatraemia (<48 hours' duration) with severe neurological 290 symptoms:………………………………………………………………………. Chronic hyponatraemia (>48 hours or unknown duration) with severe 291 neurological symptoms, serum sodium <125 mmole/L ………………………... Persistent chronic SIADH………………………………………………………. 292 Cerebral salt wasting syndrome (CSWS)……………………………………..... 293 Hyperpituitarism ……………………………………………………………...... 294 xii Blueprint in Pediatric Endocrinology

Excess growth hormone secretion and pituitary gigantism ……………………. 295 Diagnosis of growth hormone excess…………………………………………... 296 Treatment of growth hormone over secretion………………………………….. 297 Prolactinoma …………………………………………………………………… 299 Corticotropinoma ………………………………………………………………. 299 Chapter 8: Diabetes in children and adolescents Diagnosis of diabetes mellutis …………………………………………………. 305 Type 1 Diabetes Mellitus ………………………………………………………. 305 Management of type 1 Diabetes Mellitus …………………………………...…. 314 Management of T1DM in toddlers……………………………………………... 315 Fear of Hypoglycemia in Toddlers……………………………………………... 316 Principles of insulin therapy……………………………………………………. 320 Nutritional Therapy in DM……………………………………………………... 326 Exercise in DM…………………………………………………………………. 327 Psychosocial Support in DM…………………………………………………… 328 Obesity and type 2 DM (T2DM)……………………………………………….. 328 T2DM management ……………………………………………………………. 330 Impaired glucose tolerance……………………………………………………... 333 Diabetes Ketoacidosis (DKA)………………………………………...………… 334 Insulin infusion ……………………………………………………..………….. 338 Electrolyte replacement in DM………………………………………...……….. 339 Acid-base status ………………………………………………………...……… 341 Management of the ketoacidosis recovery phase ………………………………. 342 Management of Diabetes in children and adolescents during surgery or procedures that require fasting………………………………………………….. 345 Hypoglycemia ………………………………………………………………...... 347 Screening for Diabetes-Related Complications ………………………………... 348 Screening for other autoimmune diseases in T1DM……………………………. 349 Treatment of diabetic complications …………………………………………… 350

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Chapter 9: Hypoglycemia in Children and Adolescents Introduction……………………………………………………………………… 353 Hyperinsulinism ………………………………………………………………... 354 Mechanism of normal insulin secretion………………………………………… 356 Beckwith-Weidman syndrome:………………………………………………… 359 Substrate Limited Ketotic Hypoglycemia ……………………………………… 362 Branched-Chain Ketonuria (Maple Syrup Urine Disease) …………………….. 363 Glycogen Storage Disease ……………………………………………………... 364 Glucose-6-Phosphatase Deficiency (Type 1 Glycogen Storage Disease) ……... 364 Disorders of Gluconeogenesis ………………………………………………..... 364 Salicylate intoxication ………………………………………………………..... 365 Defects in Glucose Transporters ……………………………………………...... 365 Diagnosis………………………………………………………………………... 366 Treatment………………………………………………………………………... 368 Chapter 10: Adrenal Disorders Introduction:……………………………………………………………………... 373 Congenital Adrenal hyperplasia………...………………………………………. 373 CAH Forms and characteristics of different enzyme deficiencies……………… 376 Non-Classical CAH……………………………………………………………... 378 Diagnosis………………………………………………………………………... 379 Prader score for genital ambiguity……………………………………………… 379 Treatment of Adrenal Crisis…………………………………………………...... 380 Non –Classical CAH (NCAH)…………………………………………………... 387 Adrenal insufficiency…………………………………………………………… 390 Causes of primary adrenal insufficiency ……………………………………..... 391 Causes of secondary and tertiary adrenal insufficiency ………………………... 395 Clinical manifestations of adrenal insufficiency………………………………... 395 Glucocorticoid deficiency………………………………………………………. 396 Mineralocorticoid deficiency…………………………………………………… 396 Androgen deficiency……………………………………………………………. 396 Dynamic tests…………………………………………………………………… 396 xiv Blueprint in Pediatric Endocrinology

Short synacthen test…………………………………………………………….. 397 Prolonged synacthen test……………………………………………………….. 397 Tests of ACTH secretory ability………………………………………………... 398 Cushing‘s syndrome ……………………………………………………………. 401 Causes of Cushing's syndrome………………………………………………..... 402 Pseudocushing's syndrome……………………………………………………... 403 Screening of Cushing's syndrome ……………………………………………… 404 Causes of Mineralocorticoid Deficiency ……………………………………..... 410 Primary hypoalosteronism (Aldosterone synthase) deficiency…………………. 411 Mineralocorticoid resistance (Pseudohypoaldosteronism type 1, PHA1)……… 412 Pseudohypoaldosteronism Type II …………………………………………….. 413 Primary hyperaldosteronism……………………………………………………. 414 Pheochromocytoma …………………………………………………………….. 417 Chapter 11: Pediatric Obesity and Hyperlipidemia Definition of pedatric obesity…………………………………………………... 428 Etiology pedatric obesity……………………………………………………….. 430 Indices of body fat……………………………………………………………… 435 Approach to Obese Children and Adolescents ………………………………… 437 Lifestyle modification for Overweight and Obese children and adolescents…... 440 Dyslipidemia in children……………………………………………………….. 442 Characteristics of Some Primary Genetic Dyslipidemia……………………….. 444 Characteristics of some secondary dyslipidemia……………………………...... 448 Hypercholesterolemia ………………………………………………………...... 451 Hypertriglyceridemia …………………………………………………………... 453 Hyperchylomicronemia ………………………………………………………… 454

Table of Contents xv

Foreword to The First Edition

The aim of this book is to establish an effective studying reference in the clinical practice of pediatric endocrinology. It will serve as a valuable reference for medical students, interns, residents in training programs, family physicians, pediatricians, endocrine fellows and other health professionals, covering practical considerations in the diagnosis and treatment of pediatric endocrine disorders. The book has practical clinical approach, yet it provides comprehensive coverage of all the major endocrine glands and diseases. The content of each of the various chapters is fully inclusive, which augments the value of the presentation of each subject. Furthermore, the balance between the clinical material and the physiology, pathophysiology, and treatment information is ideal.

Abdulmoein Al-Agha, FRCPCH

xv xvi Blueprint in Pediatric Endocrinology

Table of Contents xvii

Preface

This book of Pediatric Endocrinology provides a good understanding of endocrine problems in infants and children, their diagnosis and their evidence-based treatment. The expanding vast horizons of pediatric endocrinology could not be limited to a single book; however, this book depicts the major key topics of pediatric endocrinology and is aimed at medical students, general practitioners and pediatricians. This book tackles a series of expanded endocrine topics. Such topics were deemed to be essential inclusions for this book, reflecting the importance of the endocrinopathies and their consequences in pediatric populations throughout the developing and developed world, and the significant time commitment to management by pediatric endocrinologists. This book is divided into seamless sections covering the topics of bone mineral metabolism, ambiguous genitalia, abnormalities of thyroid function, series of sections on speciﬁc disorders in childhood follows, including growth, posterior pituitary, diabetes mellitus, hypoglycemia, and the adrenal cortex in children and adolescents are also available in this book. From an editor‘s point of view, it has been a pleasure writing this blueprint of pediatric endocrinology, which embiggens my years of experience, several publications and medical knowledge. As always, we welcome your input to improve the value of this book.

Important notice that, all photos in this book, consents from patients have been taken.

Abdulmoein Al-Agha, FRCPCH Jeddah, Kingdom of Saudi Arabia [email protected] 2012

xix xviii Blueprint in Pediatric Endocrinology

Table of Contents xix

Acknowledgment

I gratefully acknowledge the contributions of my colleages Doctor Ihab Ahmed & Ali Harold Ocheltree. They provided a valuable assistance in both the organization and the revision of this book's contents.

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xx Blueprint in Pediatric Endocrinology

Chapter 1

Basic Endocrinology

. Introduction . Effects of hormones . Types of hormones o Amines o Peptide and protein o Steroids . Hormone receptors . Types of Hormone Receptors o G protein-coupled receptors (GPCRs) . G protein-coupled receptors mutations and endocrine diseases o Loss – of – function mutations o Gain – of – function mutations . Fetal Brain Programming . Hypothalamic-Pituitary Relationships . Hypothalamic Controls . Anterior Pituitary Function . Adrenocorticotropic hormone . Thyroid-stimulating hormone . Luteinizing hormone and follicle-stimulating hormone . Growth hormone . Prolactin . Other hormones (POMC, MSH) . Posterior Pituitary Function . Antidiuretic hormone . Oxytocin

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Blueprint in Pediatric Endocrinology 3

Introduction ‗Hormone‘ derives from the Greek woard, meaning ‗exciting‘ or ‗setting in motion‘. Ernest Starling (1866 – 1927) is regarded as the founder of endocrinology. Endocrine disorders are common in Eastern societies including Saudi Arabia. There are several examples of common endocrine diseases especially hereditary endocrinopathies due to high rate of consanguinity. An increasing number of the population has type 1 especially those who are under age of four with no reasonable explanations. In the recent years, obesity is growing problem in Saudi Arabia with more cases of type 2 diabetes. Vitamin D deficiency is by far one of the major health problems seen in outpatient clinics despite heavy sun and wide availability of diary products in Saudi Arabia. Effects of Hormones Hormones have the following effects on the body as stimulation or inhibition of growth, mood swings, induction or suppression of apoptosis (programmed cell death), activation or inhibition of the immune system, regulation of metabolism, preparation of the body for mating, fighting, fleeing, and other activity, preparation of the body for a new phase of life, such as puberty, parenting, and control of the reproductive cycle. Types of Hormones Amines Amines, such as norepinephrine, epinephrine, and dopamine, are derived from single amino acids, which is tyrosine. Thyroid hormones such as triiodothyronine (T3) and tetraiodothyronine (thyroxin, T4) make up a subset of this class because they are derived from the combination of two iodinated tyrosine amino acid residues. Peptide and Protein Peptide hormones are made of chains of amino acids. Some of these are very small indeed; the hypothalamic hormone thyrotropin releasing hormone (TRH) is only three aminoacids long, whereas the pituitary hormone whose release stimulates thyroid, stimulating hormone, TSH) is a large glycoprotein with a molecular weight of around 30 000 Daltons.

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All hormones secreted by the pituitary gland are peptide hormones, as are leptin from adipocytes, ghrelin from the stomach, and insulin from the pancreas. Steroids Steroid hormones are converted from their parent compound, cholesterol. Mammalian steroid hormones can be grouped into five groups by the receptors to which they bind: Glucocorticoids, mineralocorticoids, androgens, estrogens, and progestagens. The steroids are formed by metabolism of cholesterol by enzymes within the steroid- secreting cell, located either within the mitochondria or the smooth endoplasmic reticulum. Cells which are involved in steroid hormone production are distinctive under microscopy because of the presence of unusually large amounts of smooth endoplasmic reticulum and mitochondria. . Classically, hormones travel from the cells where they are made, in the bloodstream, to reach the cells where they act. . Some hormones also act locally, on different cell types in the tissue where they are produced. This is termed a ‗paracrine‘ effect. . Other hormones act directly on the same type of cell that secretes them. This is termed an ‗autocrine‘ action. . Hormones may have a mixture of different types of action, e.g. Testosterone, which exerts a paracrine effect on spermatogenesis in the testis, but an endocrine effect on other tissues. When excess hormone is present, a negative feedback loop is initiated such that further hormone production is inhibited. Most hormones have this type of regulatory control. However, a few hormones operate on a positive feedback cycle such that high levels of the particular hormone will activate release of another hormone. With this type of feedback loop, the end result is usually that the second hormone released will eventually decrease the initial hormone's secretion. An example of positive feedback regulation occurs in the female menstrual cycle, where high levels of estrogen stimulate release of the pituitary hormone, luteinizing hormone. All hormones are influenced by numerous factors. The hypothalamus can release inhibitory or stimulatory hormones that determine pituitary function. Blueprint in Pediatric Endocrinology 5

Hormone receptors Binding of hormones to its receptors often trigger the start of a biophysical signal that can lead to further signal transduction pathways, or trigger the activation or inhibition of genes. Types of Hormone Receptors Peptide hormone receptors are often transmembrane proteins. They are also called G-protein-coupled receptors. These receptors generally function via intracellular second messengers, including cyclic AMP (cAMP), inositol 1,4,5-trisphosphate (IP3) and the calcium - calmodulin system (Figure 1).

Fig. (1-1): Showing G-protein-coupled receptor Steroid hormone receptors are generally soluble proteins that function through gene activation. Their response elements are DNA sequences (promoters) that are bound by the complex of the steroid bound to its receptor. These receptors include those for glucocorticoids, estrogens, androgens, thyroid hormone, calcitriol (the active form of vitamin D), and the retinoid (vitamin A).

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Fig.( 1-2): Lipid Soluble Hormone Receptor.

G Protein-Coupled Receptors (GPCRs) Comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal transduction pathways and, ultimately, cellular responses. There are two principal signal transduction pathways involving the G protein-coupled receptors: the cAMP signal pathway and the Phosphatidylinositol signal pathway. The GPCR can then activate an associated G-protein by exchanging its bound GDP for a GTP. The G-protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type (Gαs, Gαi/o, Gαq/11, Gα12/13). All members of the GPCR super family share a common structural feature: seven membrane-spanning helices connected by three intracellular loops and three extracellular loops with an extracellular amino terminus and an intracellular carboxy terminus. Of these, family 1 is the largest and includes receptors for thyroid stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Family 2 shows essentially no sequence homology to family 1, members include receptors for peptide hormones, such as parathyroid hormone (PTH), parathyroid hormone–related protein (PTHrP), and Blueprint in Pediatric Endocrinology 7

calcitonin. Family 3 members include an extracellular calcium-sensing receptor. G protein-Coupled Receptors Mutations and Endocrine Diseases Over the past 20 years, naturally occurring mutations that affect G protein-coupled receptors (GPCR) have been identified, mainly in patients with endocrine diseases. Mutations in the gene encoding the α subunit of the G protein–coupling receptors to stimulation of adenylyl cyclase cause developmental abnormalities of bone, as well as hormone resistance (pseudohypoparathyroidism caused by loss-of function mutations) and hormone hypersecretion (McCune-Albright syndrome caused by gain-of-function mutations). Loss and gain-of-function mutations in (GPCR) have been identified as the cause of an increasing number of retinal, endocrine, metabolic, and developmental disorders. In endocrine signaling, loss-of-function mutations mimic hormone deficiency, whereas gain-of-function mutations mimic states of hormone excess. Loss – of – Function Mutations Loss of- function mutations of receptors for ACTH, TSH, FSH, and gonadotropin-releasing hormone (GnRH), thyrotropin-releasing hormone (TRH), and growth hormone–releasing hormone (GHRH) mimic deficiency of the respective hormones. . Subjects with heterozygous loss-of-function mutations of the TSH receptor gene are generally euthyroid with compensatory elevated serum TSH, but homozygous mutations result in congenital hypothyroidism associated with a hypoplastic or even absent thyroid gland. . Loss-of-function mutations of both copies of the LH receptor gene cause a rare form of 46, XY DSD known as Leydig cell hypoplasia. . Absence of functional PTH/PTHrP receptors causes a rare, lethal form of dwarfism known as Blomstrand chondrodysplasia. . X-linked nephrogenic diabetes insipidus (renal vasopressin resistance) is caused by loss-of-function mutations in the V2 vasopressin receptor gene located on the X chromosome. Males inheriting a mutant gene develop the disease, whereas most females do not show overt disease because random X inactivation results, on average, in 50% normal receptor genes. Identification of the mutation in carrier females 8 Chapter 1: Basic Endocrionology

facilitates early treatment of affected male neonates to avoid hypernatremia and brain damage. . In familial hypocalciuric hypercalcemia, there is relative resistance to extracellular calcium sensing receptor action caused by loss-of- function mutation of one copy of the gene encoding the calcium sensing receptor that controls PTH secretion from the parathyroid and reabsorption of calcium by the kidney. If two defective copies are inherited, extreme calcium resistance causing neonatal severe primary hyperparathyroidism results. . Loss-of-function mutations in the gene encoding the melanocortin 4 receptor, which regulates hypothalamic pathways controlling appetite and energy metabolism, result in a distinct obesity syndrome characterized by hyperphagia and increased linear growth. Examples Tabe1 (1-1): Showing Different Examples of Loss-of-Function Mutations

Disease Mode of inheritance Germ line mutation Arginine vasopressin Nephrogenic diabetes insipidus X-linked recessive receptor 2

Familial hypogonadism Luteinizing hormone Leydig cell hypoplasia (males) Autosomal recessive receptor Primary amenorrhea (females) Central hypogonadotrophic Gonadotropin-releasing Autosomal recessive hypogonadism hormone receptor Thyrotropin-releasing Central hypothyroidism Autosomal recessive hormone receptor Benign familial hypocalciuric Calcium-sensing Autosomal dominant hypercalcemia receptor Neonatal severe primary Calcium-sensing Autosomal recessive hyperparathyroidism receptor

Gain – of – Function Mutations Gain-of-function mutations in the LH and TSH receptor genes may mimic states of hormone excess; familial male precocious puberty, and familial non autoimmune hyperthyroidism, respectively. Females Blueprint in Pediatric Endocrinology 9

inheriting gain-of-function mutations in the LH receptor gene do not show precocious puberty because, unlike in males, the combined action of LH and FSH is required for female pubertal development. Examples Table (1-2): Showing Examples of Gain-of-Function Mutations

Disease Mode of inheritance Mutation

Nephrogenic syndrome of Arginine vasopressin Sex –linked dominant inappropriate antidiuresis receptor 2

Male-limited precocious Luteinizing hormone Autosomal dominant puberty receptor

In females: spontaneous Follicle stimulating ovarian hyperstimulation Autosomal dominant hormone receptor syndrome

Non autoimmune familial Autosomal dominant TSH receptor hyperthyroidism

Parathyroid hormone and Jansen metaphyseal Autosomal dominant parathyroid related chondrodysplasia protein receptors

Familial hypocalcemic hypercalciuria (autosomal Autosomal dominant Calcium-sensing receptor dominant hypoparathyroidism)

Leydig cell adenomas with Luteinizing hormone Sporadic precocious puberty receptor

Autonomous thyroid Sporadic TSH receptor adenomas (rare carcinomas)

Fetal Brain Programming A large body of human epidemiological data, as well as experimental studies, suggest that environmental factors operating early in life potently affect developing systems, permanently altering structure and function throughout life. This process has been called `programming'. The brain is 10 Chapter 1: Basic Endocrionology

a key target for such effects. This review focuses on the effects of adverse early environments, notably exposure to stress or glucocorticoid, upon subsequent childhood and adult hypothalamus-pituitary-adrenal axis activity, behavior and cognition. The data suggest that key targets for programming include glucocorticoid receptor gene expression and the corticotrophin-releasing hormone system. Approaches to minimize or reverse the consequences of such early life events may have therapeutic importance. Good example of endocrine fetal brain programming is what has been observed in female fetuses who have been exposed intrauterine to excessive androgens due to for example congenital adrenal hyperplasia, which has diverse effects not only on external genitalia but also on the fetal brain with childhood and adult male type of behavior. The Endocrine System Hypothalamic-Pituitary Relationships The interaction between the hypothalamus and pituitary (hypothalamic-pituitary axis) is a feedback control system. The hypothalamus receives input from virtually all other areas of the CNS and uses it to provide input to the pituitary. In response, the pituitary releases various hormones that stimulate certain endocrine glands throughout the body. Changes in circulating levels of hormones produced by these endocrine glands are detected by the hypothalamus, which then increases or decreases its stimulation of the pituitary to maintain homeostasis. The hypothalamus modulates the activities of the anterior and posterior lobes of the pituitary in different ways. Neurohormones synthesized in the hypothalamus reach the anterior pituitary (adenohypophysis) through a specialized portal vascular system and regulate synthesis and release of the six major peptide hormones of the anterior pituitary. These anterior pituitary hormones regulate peripheral endocrine glands (the thyroid, adrenals, and gonads) as well as growth and lactation. No direct neural connection exists between the hypothalamus and the anterior pituitary. In contrast, the posterior pituitary (Neurohypophysis) comprises axons originating from neuronal cell bodies located in the hypothalamus. These axons serve as storage sites for two peptide hormones synthesized in the hypothalamus; these Blueprint in Pediatric Endocrinology 11

hormones act in the periphery to regulate water balance, milk ejection, and uterine contraction. Virtually all hormones produced by the hypothalamus and the pituitary are released in a pulsatile fashion; periods of such release are interspersed with periods of inactivity. Some hormones (e.g., adrenocorticotropic hormone, growth hormone, and prolactin) have definite circadian rhythms; others (e.g., luteinizing hormone and follicle- stimulating hormone during the menstrual cycle) have month-long rhythms with superimposed circadian rhythms. Hypothalamic Controls Regulation of most anterior pituitary hormones depends on stimulatory signals from the hypothalamus; the exception is prolactin, which is regulated by inhibitory stimuli. If the pituitary stalk (which connects the pituitary to the hypothalamus) is severed, prolactin release increases, whereas release of all other anterior pituitary hormones decreases. Many hypothalamic abnormalities (including tumors and encephalitis and other inflammatory lesions) can alter the release of hypothalamic neurohormones. Because neurohormones are synthesized in different centers within the hypothalamus, some disorders affect only one neuropeptide, whereas others affect several. The result can be undersecretion or oversecretion of neurohormones. Anterior Pituitary Function The cells of the anterior lobe (which constitutes 80% of the pituitary by weight) synthesize and release several hormones necessary for normal growth and development and also stimulate the activity of several target glands. Adrenocorticotropic Hormone (ACTH) Corticotrophin-releasing hormone (CRH) is the primary stimulator of ACTH release, but antidiuretic hormone plays a role during stress. ACTH induces the adrenal cortex to release cortisol and several weak androgens, such as dehydroepiandrosterone (DHEA). Circulating cortisol and other corticosteroids (including exogenous corticosteroids) inhibit the release of CRH and ACTH. The CRH-ACTH-cortisol axis is a central component of the response to stress. Without ACTH, the adrenal cortex atrophies and cortisol release virtually ceases. 12 Chapter 1: Basic Endocrionology

Thyroid-stimulating hormone (TSH) TSH regulates the structure and function of the thyroid gland and stimulates synthesis and release of thyroid hormones. TSH synthesis and release are stimulated by the hypothalamic hormone thyrotropin- releasing hormone (TRH) and suppressed (negative feedback) by circulating thyroid hormones. Luteinizing Hormone (LH) & Follicle stimulating Hormone (FSH) LH and FSH control the production of the sex hormones. Synthesis and release of LH and FSH are stimulated by gonadotropin-releasing hormone (GnRH) and suppressed by estrogen and testosterone. In females, LH and FSH stimulate ovarian follicular development and ovulation. In males, FSH acts on Sertoli cells and is essential for spermatogenesis; LH acts on Leydig cells of the testes to stimulate testosterone biosynthesis Growth Hormone (GH) GH stimulates somatic growth and regulates metabolism. Growth hormone releasing hormone (GHRH) is the major stimulator and somatostatin is the major inhibitor of the synthesis and release of GH. GH controls synthesis of insulin-like growth factor 1 (IGF-1, also called somatomedin-C), which largely controls growth. Although IGF-1 is produced by many tissues, the liver is the major source. A variant of IGF- 1 occurs in muscle, where it plays a role in enhancing muscle strength. It is less under control of GH than is the liver variant. The metabolic effects of GH are biphasic. GH initially exerts insulin- like effects, increasing glucose uptake in muscle and fat, stimulating amino acid uptake and protein synthesis in liver and muscle, and inhibiting lipolysis in adipose tissue. Several hours later, more profound anti–insulin-like metabolic effects occur. They include inhibition of glucose uptake and use, causing blood glucose and lipolysis to increase, which increases plasma free fatty acids. GH levels increase during fasting, maintaining blood glucose levels and mobilizing fat as an alternative metabolic fuel. Production of GH decreases with aging. Ghrelin, a hormone produced in the fundus of the stomach, promotes GH release from the pituitary, increases food intake, and improves memory. Blueprint in Pediatric Endocrinology 13

Prolactin Prolactin is produced by lactotroph cells that constitute about 30% of the cells of the anterior pituitary. In humans, the major function of prolactin is stimulating milk production. Also, prolactin release occurs during sexual activity and stress. Prolactin may be a sensitive indicator of pituitary dysfunction; prolactin is the hormone most frequently produced in excess by pituitary tumors, and it may be one of the hormones to become deficient from infiltrative disease or tumor compression of the pituitary. Other Hormones Several other hormones are produced by the anterior pituitary. These include pro-opiomelanocortin (POMC, which gives rise to ACTH), α- and β-melanocyte-stimulating hormone (MSH). POMC and MSH can cause hyperpigmentation of the skin and are significant clinically in disorders in which ACTH levels are markedly elevated (e.g., Addison's disease, Nelson syndrome), β-lipotropin (β-LPH), the enkephalins, and the endorphins. The function of β-LPH is unknown. Enkephalins and endorphins are endogenous opioids that bind to and activate opioids receptors throughout the CNS. Posterior Pituitary Function The posterior pituitary releases Antidiuretic hormone (arginine vasopressin) and oxytocin. Both hormones are released in response to neural impulses and have half-life is short of about 10 minutes. Antidiuretic Hormone (ADH) ADH acts primarily to promote water conservation by the kidney by increasing the permeability of the distal tubular epithelium to water. At high concentrations, ADH also causes vasoconstriction. ADH plays an important role in maintaining fluid homeostasis and vascular and cellular hydration. The main stimulus for ADH release is increased osmotic pressure of water in the body, which is sensed by osmoreceptors in the hypothalamus. The other major stimulus is volume depletion, which is sensed by baroreceptors in the left atrium, pulmonary veins, carotid sinus, and aortic arch, and then transmitted to the CNS through the vagus and glossopharyngeal nerves. Other stimulants for ADH release include pain, stress, emesis, hypoxia, exercise, hypoglycemia, cholinergic 14 Chapter 1: Basic Endocrionology

agonists, β-blockers, angiotensin, and prostaglandins. Inhibitors of ADH release include α-blockers, and glucocorticoids.Lack of ADH secretion causes central diabetes insipidus; while an inability of the kidneys to respond normally to ADH causes nephrogenic diabetes insipidus. Removal of the pituitary gland usually does not result in permanent diabetes insipidus because some of the remaining hypothalamic neurons produce small amounts of ADH. Excess of ADH secretion produces syndrome of inappropriate ADH secretion (SIADH). Oxytocin Oxytocin has two major targets: the myoepithelial cells of the breast, which surround the alveoli of the mammary gland, and the smooth muscle cells of the uterus. Suckling stimulates the production of oxytocin, which causes the myoepithelial cells to contract. This contraction causes milk to move from the alveoli to large sinuses for ejection (milk letdown reflex of nursing mothers). Oxytocin stimulates contraction of uterine smooth muscle cells. There is no recognized stimulus for oxytocin release in men, although men have extremely low levels.

Chapter 2

Disorders of Calcium and Bone Metabolism

. Introduction . Vitamin D and its metabolism . Parathyroid glands . Calcitonin . The calcium-sensing receptor (CaSR) . Parathyroid Hormone–Related Peptide (PTHrP) . Hypocalcaemia . Hypocalcaemia in neonates o Early neonatal hypocalcaemia o Late neonatal hypocalcaemia . Hypocalcaemia in infants & children . Clinical manifestations of Hypocalcaemia . Investigations of Hypocalcaemia . Rickets and Osteomalacia . Various Causes of Rickets o Hypocalcemic rickets o Hypophosphatemic rickets o Congenital rickets o Nutritional rickets o Drug-induced rickets . Clinical features of Rickets . Investigations of vitamin D deficiency . Treatment of vitamin D deficiency o Vitamin D replacement o Sun exposure o Calcium and phosphate replacement o Dosing Recommendations . Vitamin D–dependent rickets (type I) . Vitamin D-resistant rickets (type II vitamin D–dependent rickets) . Hypophosphatemic Rickets . Hypophosphatasia . Treatment of Hypophosphatasia . Fanconi's syndrome

17 16 Chapter 2: Disorders of Calcium and Bone Metabolism

. McCune-Albright syndrome . Renal Osteodystrophy (Renal Rickets) . Hepatic Rickets . Malabsorption & Rickets . Oncogenic Osteomalacia . Hypoparathyroidism . Causes of Hypoparathyroidism o Transient Hypoparathyroidism o Permanent hypoparathyroidism . Acquired hypoparathyroidism . Treatment of hypoparathyroidism . Complications of hypoparathyroidism . Pseudohypoparathyroidism o Clinical features o Investigations . Pseudopseudohypoparathyroidism . Treatment of Pseudopseudohypoparathyroidism . Hypomagnesaemia . Hypercalcemia in children o Causes of hypercalcemia in infants o Causes of hypercalcemia in children o Investigations . Oncogenic Hypercalcemia . Clinical manifestations of hypercalcemia . Treatment of Hypercalcemia . Osteoporosis in children and adolescence . Primary osteoporosis o Osteogenesis imperfecta (OI) o Idiopathic juvenile osteoporosis . Secondary osteoporosis . Investigations of osteoprosis . Prevention and therapy of osteoporosis

Introductiom The two most important hormones for maintaining calcium levels in the body are parathyroid hormone (PTH) and 1, 25(OH) 2 D (the active form of vitamin D). The major regulator is PTH, which is part of a negative feedback loop to maintain normocalcemia. Vitamin D is a steroid hormone and interacts with vitamin D receptor which is a member of the steroid hormone receptor family. The main function of 1, 25(OH) 2 vitamin D is to support the circulating calcium concentration through two actions. The first is to stimulate calcium absorption from the gut lumen by enterocytes, enhances the absorption of phosphorus from the diet. The second action of 1, 25(OH) 2 vitamin D is to increase bone resorption by stimulating osteoblast activity.

The two main sources of vitamin D in humans are vitamin D3 (cholecalciferol), produced by the skin after UV radiation (290-320 nm) dependent conversion of 7-dehydrocholesterol, and dietary intake of either vitamin D2 (ergocalciferol) or vitamin D3. Both have identical biological actions. Foods contain vitamin D, including oily fish and cod liver oil, fortified foods, including certain cereals, milk, egg yolk and bread.

Fig. (2-1): Showing Sun is The Main Source of Vitamin D.

17 18 Chapter 2: Disorders of Calcium and Bone Metabolism

Vitamin D Metabolism In response to ultraviolet light, keratinocytes in the epidermis convert 7-dehydrocholesterol, the immediate precursor of cholesterol, into vitamin D3. Cutaneous production of vitamin D3 is affected by a variety of factors such as latitude, season, use of sunscreen, concentration of melanin, and type of clothing, all of which vary the amount of ultraviolet light that penetrates the skin. The initial step in the metabolic activation process is production of a 25 hydroxy vitamin D3 by 25-hydroxylase enzyme in the liver. Further hydroxylation of these metabolites occurs in the mitochondria of kidney tissue, catalyzed by renal 25-hydroxyvitamin D by 1α-hydroxylase enzyme to produce calcitriol (1, 25[OH] 2 D3), which is the biologically active form of vitamin D3.

Fig. (2-2): Showing Steps of Vitamin D Metabolism. Blueprint in Pediatric Endocrinology 19

Vitamin D is absorbed from the small intestine, along with dietary fat, which is why fat malabsorption resulting from various diseases (e.g., cystic fibrosis, celiac disease) are associated with poor absorption of all fat soluble vitamins including vitamin D. Fat-soluble vitamins are primarily stored in the liver and adipose tissue. Decreased levels of vitamin D lead to insufficient intestinal absorption of calcium, followed by an increased secretion of PTH (secondary hyperparathyroidism). Increased PTH stimulates calcium release from bone and decreases calcium clearance by the kidney, thus increasing the calcium levels in the circulation. If hypovitaminosis D persists, severe hypocalcaemia may occur. Malnutrition is the most common cause of Vitamin D deficiency. It is usually related to poverty and the educational level of the family. Parathyroid Glands The four parathyroid glands are located in the neck, closely opposed to the posterior capsule of the four poles of the thyroid gland. Embryologically, they are derivatives of the third and fourth branchial pouches. The pair of glands located at the upper poles of the thyroid is derived from the fourth pouch, whereas those located at the lower poles migrate downward from the third pouch, along with the thymus gland. Extra parathyroid glands in aberrant locations are not uncommon, especially along the path of embryologic migration. The parathyroid hormone is an 84-amino acid protein encoded by a single gene. The secretion of PTH is regulated by the extracellular ionized calcium concentration. PTH exerts direct effects on kidney and bone cells and indirect effects on enterocytes. In the kidney, PTH has three principal effects; acts on proximal tubular cells to inhibit the reabsorption of phosphate, stimulates the activity of the renal 1α- hydroxylase in proximal tubular cells. This leads to the formation of biologically active 1, 25(OH) 2 vitamin D from its circulating precursor 25(OH) vitamin D. Finally, PTH acts to increase the reabsorption of calcium by the kidney. In the skeleton, PTH activates bone turnover and liberates stored calcium. 20 Chapter 2: Disorders of Calcium and Bone Metabolism

Fig. (2-3): Showing Calcium Homeostatsis. Calcitonin Calcitonin is a 32-amino acid linear polypeptide hormone that is produced primarily by the parafollicular cells (also known as C-cells) of the thyroid. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH). Secretion of calcitonin is stimulated by an increase in serum calcium, gastrin and pentagastrin. calcitonin lowers blood calcium levels in three ways; it inhibits calcium absorption by the intestines, inhibits osteoclast activity in bones, inhibits renal tubular cell resorption of calcium allowing it to be secreted in the urine. Calcitonin protects against calcium loss from skeleton during periods of calcium mobilization, such as pregnancy and, especially, lactation. The calcitonin receptor, found on osteoclasts, and in kidney and regions of the brain, is a G protein-coupled receptor.

Blueprint in Pediatric Endocrinology 21

The Calcium- Sensing Receptor (CaSR) G- protein coupled receptor which senses extracellular levels of calcium In the parathyroid gland, the calcium-sensing receptor controls calcium homeostasis by regulating the release of parathyroid hormone (PTH). The release of PTH is inhibited in response to elevations in plasma calcium concentrations and activation of the calcium receptor. So far, several different activating and inactivating mutations have been described in the extracellular, transmembrarane and intracellular c- terminal tail of the receptor. Activation mutations in CaSR lead to hypocalcemia, where renal tubular absorbtion remains low even in hypocalcemia, while, inactivating mutations lead to hypercalcemia seen in familial hypocalciuric hypercalcemia and in neonatal severe hyperparathyroidism. Parathyroid Hormone–Related Peptide (PTHrP) Is a family of polypeptide hormones produced by most of tissues. PTHrP is homologous to PTH only in the first 13 amino acids of its amino terminus, 8 of which are identical to PTH. Its gene is located on the short arm of chromosome 12 and that of PTH is on the short arm of chromosome 11. It activates PTH receptors in kidney and bone cells and increases urinary cyclic adenosine monophosphate and renal production of 1, 25(OH) 2D3. It is produced in almost every type of cell of the body, including every tissue of the embryo at some stage of development. PTHrP appears to be essential for normal skeletal maturation of the fetus. PTHrP levels are increased during lactation. Breast milk and pasteurized bovine milk have levels of PTHrP that is 10,000 times higher than those of normal plasma. Most instances of the hormonal hypercalcemia syndrome of malignancy. In humans, a single gene located on chromosome 12 encodes PTHrP. The PTH and PTHrP genes share common structural features in particular, of the first 13 amino-terminal amino acids in each protein, eight are identical; after this, the sequences of the two proteins diverge completely. PTHrP is made in a variety of different cell types, is secreted locally, and acts in a paracrine or autocrine fashion to activate PTH1R on neighboring cells. Important sites of action include developing cartilage, bone, breast tissue, and various types of smooth muscle. During lactation, PTHrP is secreted by the breast into the circulation and acts like PTH to regulate systemic calcium metabolism. 22 Chapter 2: Disorders of Calcium and Bone Metabolism

Hypocalcaemia The normal range of total serum calcium is between 8.5 to 10.2 mg/dl (2.1 to 2.5 mmol/l). Hypocalcaemia is defined as a total serum calcium concentration of less than 2.1 mmole/L (8.5 mg/dl) in children, less than 2 mmole/L (8 mg/dl) in a full term neonates, and less than 1.75 mmole/L (7 mg/dl) in preterm neonates. Calcium homeostasis tightly controlled by parathyroid hormone, Calcitonin and vitamin D. Calcium is essential for cell function, cell membrane stability, neuronal transmission, bone physiology, blood homeostasis, and cell signaling. . Serum calcium exists in an ionized form (50%) and the remaining is in bound form to albumin . Only ionized calcium is biologically important

Hypocalcaemia in Neonates Early Neonatal Hpocalcaemia (48-72 hour of birth) . Prematurity and small for gestational age have a multifactorial mechanisms include poor intake, decreased responsiveness to vitamin D, increased calcitonin, and hypoalbuminemia leading to decreased total but normal ionized calcium. A transient, relative hypoparathyroidism may cause hypocalcaemia in preterm and some small-for-gestational-age neonates, who have parathyroid glands that do not yet function adequately. Hypocalcaemia occurs in as many as 30% of infants with very low birth weight (<1500 g) and in as many as 89% of infants whose gestational age of less than 32 weeks. . Birth asphyxia leads to delayed introduction of feeds, increased calcitonin production, increased endogenous phosphate load, and alkali therapy. All may contribute to hypocalcaemia. . Diabetes mellitus in the mother causes hypomagnesaemia with secondary functional hypoparathyroidism and hypocalcaemia in the infant. A high incidence of birth asphyxia and prematurity in infants of diabetic mothers are also contributing factors.

Blueprint in Pediatric Endocrinology 23

Late Neonatal Hypocalcaemia (3-7 Days of birth & as late as 6 weeks of age) . Exogenous phosphate load which is the most commonly seen in developing countries. Feeding with phosphate-rich formula or whole cow's milk which has seven times phosphate load of breast milk. . Magnesium deficiency leads to functional hypoparathyroidism. . Transient or permanent hypoparathyroidism of newborn. . Maternal hyperparathyroidism . Congenital vitamin D deficiency. . Symptoms are rarely occurring unless total serum calcium is < 7 mg/dl (< 1.75 mmole/ L) or the ionized calcium is < 3.0 mg/dl (< 0.75 mmole/L). . Signs include hypotonia, tachycardia, tachypnea, apnea, muscular pain and weakness, poor feeding, jitteriness, numbness, paresthesia, tetany, and seizures.

Hypocalcaemia in Infants & Children The most common causes of hypocalcaemia are vitamin D deficiency, chronic renal failure, hypomagnesaemia, hypoparathyroidism, pseudohypoparathyroidism and acute pancreatitis. Less frequently, causes seen in critically ill patients with sepsis, burns, and acute renal failure. Transient hypocalcaemia can be observed after administration of a number of drugs, including heparin, glucagon, and protamine, also after massive transfusions of citrated blood products. Miscellaneous Causes of Hypocalcaemia . Activation mutation of the calcium sensing receptor (CaSR) which is inherited as an autosomal dominant, results in hypocalcemia and hypomagnesemia. A gain-of-function mutation inhibits calcium reabsorption in the renal tubule, which results in urinary loss of calcium and magnesium. . Deletion 22q11.2 syndrome, where there is developmental defect of the parathyroid glands lead to hypoparathyroidism. Diagnosis is usually made by FISH analysis. Hypocalcemia is usually developed in 24 Chapter 2: Disorders of Calcium and Bone Metabolism

the neonatal period in most of cases, although hypocalcemia might be seen in infancy period. . Hyperphosphatemia occurs after massive tissue breakdown in rhabdomyolysis, after accidental ingestion of phosphate-containing drugs, or in critically ill patients. Phosphate binds to calcium, leading to acute hypocalcaemia. . Hungry bone syndrome which leads to a state of severe hypocalcaemia, often after starting vitamin D therapy in nutritional rickets which might persists for few weeks after commencing vitamin D therapy or post surgical removal of parathyroid gland. Serum calcium is rapidly taken from the circulation and deposited into the bones. . Acute pancreatitis can lead to hypocalcaemia when circulating calcium is precipitated in the pancreas as calcium soaps. . Hypocalcaemia can be induced by certain drugs: these include bisphosphonate therapy, particularly when given intravenously; chemotherapies; glucocorticoid; anticonvulsants; and chelating agents such as EDTA. . Sepsis in which up to 20% of patients have a reduction in the ionized serum calcium. Hypocalcaemia is associated with a worse prognosis. This phenomenon is most often reported with gram-negative sepsis, but it has occurred in toxic shock syndrome caused by staphylococcal infection. The pathophysiology of hypocalcaemia in this setting is unknown. Clinical Manifestations of Hypocalcaemia Manifestations of hypocalcaemia are primarily related to increased neuromuscular irritability. "Tetany is the classical sign of hypocalcaemia", but it is not always present. Paresthesia is more common and often first occurs around the mouth or in the fingertips. They may progress to overt muscle spasm in the face and extremities, the latter typified by carpopedal spasm. The term latent tetany refers to signs elicited by provocative stimuli such as ischemia. Trousseau's sign which is by induction of carpal spasm within 3 - 5 minutes of inflating a sphygmomanometer above systolic blood pressure while, Chvostek's sign is by percussion of the facial nerve to induce involuntary contraction of Blueprint in Pediatric Endocrinology 25

the facial muscles including the corner of the mouth, nose, and eye on the same side.

Fig. (2-4): Showing Both Signs of Hypocalcemia. . Basal ganglia calcifications are typical findings in long-standing hypoparathyroidism. . Osteoporosis and dental abnormalities have also been reported in chronic untreated hypoparathyroidism Investigations of Hypocalcaemia . Serum total and ionized calcium levels should be the first tests performed in patients presenting with symptoms and signs of hypocalcaemia. . Serum albumin concentration should also be tested, as over 40% of circulating calcium is bound to albumin in a ratio of 0.8 mg calcium to 1 mg albumin. This ratio is used to correct the total calcium after measuring albumin. 26 Chapter 2: Disorders of Calcium and Bone Metabolism

. Corrected serum calcium = (0.02 x (normal albumin - patient‘s albumin) + serum calcium . Intact parathyroid hormone levels should be tested in any patient with hypocalcaemia. . 25-hydroxyvitamin D, 1, 25 dihydroxyvitamin D, and alkaline phosphates levels may be useful in patients suspected of vitamin D deficiency. In classic Vitamin D deficiency, measuring 25- hydroxyvitamin D is adequate. . High levels of phosphate in the absence of renal failure and tissue breakdown indicate hypoparathyroidism or pseudohypoparathyroidism. Hypomagnesaemia can cause hypocalcaemia and may indicate the underlying etiology. Elevated urea and creatinine can indicate renal dysfunction. . Amylase and lipase levels should be checked in patients with abdominal pain. In acute pancreatitis the amylase and lipase levels are significantly increased. . ECG should be performed which may show prolonged QT intervals, that may be the only sign of hypocalcaemia. . Total lymphocyte and T-cell subset analyses: Findings are decreased in patients with DiGeorge syndrome and chest x-ray looking for the presence of thymus. . Karyotype to assess for 22q11 and 10p13 deletion in cases of hypoparathyroidism. . Maternal and family screening in familial forms of hypocalcaemia, such as those caused by activating mutations of the calcium-sensing receptor. . X-rays should be performed when multiple fractures or signs of rickets or Osteomalacia are observed. . DXA scans may be done in patients with suspected osteoporosis. Hypocalcaemia are corrected by treating the underlying disorder. Some patients require lifelong maintenance therapy for hypocalcaemia, including hypoparathyroidism, pseudohypoparathyroidism, and vitamin D–resistant states. Blueprint in Pediatric Endocrinology 27

In hypoparathyroidism, the goal is to maintain serum calcium in the low-normal range. Increasing the serum calcium level into the middle to high-normal range can result in significant hypercalciuria, nephrocalcinosis, and nephrolithiasis. In some patients with hypoparathyroidism, a thiazide diuretic may be useful in augmenting serum calcium levels and in reducing the hypercalciuria that can occur with the institution of treatment. . Long-term treatment of hypoparathyroidism with synthetic human PTH is not yet practical, although short-term therapy has been successful

Various stresses such as trauma and infection can increase the therapeutic requirements of patients with chronic hypocalcaemia, and the clinician should be alert to this possibility. There is no single best way to achieve target calcium levels, although the combination of a vitamin D metabolite with calcium supplements is generally preferred. Many different preparations of both are available. Rapid-acting preparations of vitamin D are generally preferred for the treatment of hypoparathyroidism. Calcitriol or one alpha calcidol preparations can be used in most patients. For treatment of vitamin D deficiency, infants are to be given 1,000 to 2,000 international units/day (25 to 50 mcg) and older children may be given up to 5,000 international units / day (125 mcg) for 2 to 3 months. The dose of calcitriol can range from as little as 0.25 up to 2.0 μg / day. The biologic half-life of the drug is 12 to 14 hours. When hypercalcemia develops during therapy with calcitriol, it usually resolves within 3 to 4 days after discontinuing the drug, although it can persist for more than 1 week. In addition to a high-calcium diet, calcium supplements are important for the treatment of hypoparathyroidism. One-α- hydroxycholecalciferol doses depend on the age of the child, in neonates 50-100 nanogram/kg once daily as necessary (up to 2 microgram daily), in children under 12 years of age the dose of 25-50 nanogram /kg (maximum 1 microgram daily), while children between 12-18 years dose of 1 microgram / day adjusted as necessary. Doses of 1000 to 2000 mg/day of calcium may be necessary.

28 Chapter 2: Disorders of Calcium and Bone Metabolism

Key points . Vitamin D deficiency is commonly seen in the developing countries and its supplement should be given to all age groups either as prophylactic or therapeutic doses depending on their vitamin D serum levels. . Congenital vitamin D deficiency in neonates and infants is not uncommon and best prevented by routine screening of the pregnant mothers. . Prophylactic or therapeutic doses of vitamin D during pregnancy and lactation is indicated to decrease the consequences of congenital vitamin D deficiencies in their babies especially tetany and seizures manifested because of hypocalcaemia. . Intravenous infusion with calcium-containing solutions can cause severe tissue necrosis. This can cause contractures and may require skin grafting. Integrity of the intravenous site should be ascertained before administering calcium through a peripheral vein. . Necrosis of liver can occur after calcium infusion through an umbilical vein catheter placed in a branch of the portal vein. The position of all umbilical vein catheters must be confirmed radiologically before infusing calcium-containing solutions. . Rapid infusion of calcium-containing solutions through arterial lines can cause arterial spasm and, if administered via an umbilical artery catheter, intestinal necrosis. Rickets and Osteomalacia Rickets is a disease of the growing bones in which defective mineralization occurs in both bone and cartilage of the epiphyseal growth plates. It is associated with growth retardation and skeletal deformities. Osteomalacia is a disorder of the mature bone in which mineralization of new osteoid bone is inadequate or delayed. Skeletal muscles have a vitamin D receptor and may require vitamin D for maximum function. Vitamin D deficiency causes muscle weakness. Brain, parathyroid glands, breast, and colon tissues, among others, as well as immune cells have vitamin D receptors and respond to 1, 25-dihydroxyvitamin D. Blueprint in Pediatric Endocrinology 29

. Directly or indirectly, 1, 25-dihydroxyvitamin D controls more than 200 genes, including genes responsible for the regulation of cellular proliferation, differentiation, apoptosis, and angiogenesis. . It decreases cellular proliferation of both normal cells and cancer cells and induces their terminal differentiation. . It is also a potent immunomodulator. Rickets can manifest in childhood at the distal forearm, knee, and costochondral junctions, as these are sites of rapid bone growth, where large quantities of calcium and phosphorus are required for mineralization. Characteristic features include widening of the bones at the wrists and knees, bowing of the legs, spine deformities, fractures, bone pain, and dental abnormalities. Causes of Rickets Hypocalcemic Rickets . Lack of vitamin D due to: o Decreased sun exposure o Dietary-deficient intake . Malabsorption diseases that affects absorption of vitamin D . Liver diseases (affects conversion of cholecalciferol to calcidiol) . Anticonvulsant drugs (phenytoin, phenobarbitone due to increased metabolism of vitamin D by inducing cytochrome P450 activity). . Renal Osteodystrophy as progressive renal disease is associated with a decline in serum calcium resulting from several factors. Important among these are a rise in serum phosphate as the ability of the kidney to clear absorbed phosphate declines and a fall in serum levels of 1,25(OH)2 vitamin D because of diminishing renal production of this metabolite. The consequent stimulation of parathyroid function can lead to severe secondary and even tertiary hyperparathyroidism and therefore early intervention with phosphate binders and calcitriol or calcitriol analogues. . Type 1 vitamin D-dependent rickets occurs because of a defect in one-alpha hydroxylase enzyme which is responsible for the conversion of 25-OH vitamin D into the active metabolite. 30 Chapter 2: Disorders of Calcium and Bone Metabolism

. End-organ resistance to calcitriol is very rare autosomal recessive disorder which is usually caused by mutations in the gene encoding for vitamin D receptors. This is called type 2 vitamin D-dependent rickets. Hypophosphatemic Rickets . Poor dietary intake . Malabsorption diseases. . Prematurity . Renal phosphate wasting . Hereditary hypophosphatemic rickets . Renal tubular acidosis (type II proximal) . Oncogenic hypophosphatemia Congenital Rickets Onset of this type happens in the first six months of life. It is quite rare in industrialized countries; however, it is common in developing countries, including Saudi Arabia. It occurs when there is maternal vitamin D deficiency during pregnancy. Maternal risk factors include poor dietary intake of vitamin D, lack of adequate sun exposure, and closely spaced pregnancies. These newborns may have symptomatic hypocalcaemia, intrauterine growth retardation, and decreased bone ossification, along with classic rachitic changes. Subtle maternal vitamin D deficiency may have an adverse effect on neonatal bone density and birth weight. It can also cause a defect in dental enamel, and predispose infants to neonatal hypocalcaemic tetany. Use of prenatal vitamins containing vitamin D prevents this entity as well prophylactic vitamin D supplementation from birth dose of 500 to 1000 unit/day will prevent this entity.

Nutritional Rickets Globally, nutritional deficiencies are the leading cause of rickets. Infants fed exclusively with mother's milk can develop nutritional rickets because of the low content of vitamin D in breast milk (30-40 IU/L). In premature infants, insufficient amounts of both calcium and phosphorus may cause nutritional rickets. Furthermore, reserves of vitamin D in the neonate highly depend on the mother's vitamin D status. Infants with low Blueprint in Pediatric Endocrinology 31

or no sun exposure may develop rickets, particularly if they have dark skin, because of decreased vitamin D production by the skin after exposure to UV light. Maternal hypovitaminosis D may cause congenital rickets in infants, which is commonly seen in many of developing countries including Saudi Arabia. Clinical Features In infants, clinical features of hypocalcaemia include seizures, apnea, and tetany. In children, clinical features of rickets include delayed motor milestones, hypotonia, enlargement of wrists, progressive bowing of long bones, rachitic rosary, Harrison sulcus, late closure of anterior fontanel, parietal and frontal bossing, craniotabes, delay in teeth eruption, enamel hypoplasia, decreased bone mineral density, myopathy with normal deep tendon reflexes, and propensity for infections (as a consequence of impaired phagocytosis and neutrophil motility).

Fig. (2-5): Showing Bilateral Bowing of Lower Limbs

Fractures occur in older infants and toddlers with overt rickets and can be seen using radiography. Radiological features include widening of the epiphyseal plates, cupping, and deformities in the shaft of long bones. The healing process is characterized by broadened bands of increased density. 32 Chapter 2: Disorders of Calcium and Bone Metabolism

. Recent studies documenting the high prevalence of vitamin D deficiency and the need to increase dietary vitamin D intake. . Epidemiological studies and new information on the role of vitamin D in preventing autoimmune diseases, cardiovascular disease, and cancer. . Prospective and retrospective epidemiologic studies all indicate that levels of 25-hydroxyvitamin D below 20 ng/milliliter are associated with a 30 to 50% increased incident risk of colon, prostate, and breast cancer, along with higher mortality from these cancers.

Fig. (2-6): Showing Knock Knee (left), Radiological Changes (Right) Treatment of Vitamin D Deficiency Correction of vitamin D deficiency and insufficiency in children will promote growth and deposition of calcium into the skeleton. Children with skeletal manifestations of rickets should be aggressively treated. The earlier the intervention, the more likely a favourable prognosis, with resolution of many of the associated skeletal deformities. This is especially true for deformities in the legs. Correction of vitamin D Blueprint in Pediatric Endocrinology 33

deficiency in adolescents improves bone mineral density and stimulates mineralization of the collagen matrix, resulting in resolution of bone pain associated with osteomalacia. Vitamin D- Replacement Based on all the available medical and scientific literature, to obtain the maximum benefit of vitamin D for overall health and well-being, children and adults should have a level of serum 25-hydroxyvitamin D of >75 nmol/L (>30 nanogram/ml). The amount of vitamin D required to achieve this depends on a wide variety of factors, including age, baseline 25-hydroxyvitamin D, BMI, sun-exposure history, and the use of medications that can affect vitamin D metabolism and intestinal absorption. The mainstay of treatment is the provision of vitamin D to correct the causative deficiency. The goal is to reach and maintain a serum 25- hydroxyvitamin D level in both children and adults of between 75 and 250 nmol/l (30 and 100 nanogram/ml). Vitamin D deficiency in adolescents and children is corrected by treatment with vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol) given orally for 8 to 12 weeks, followed by a lower maintenance dose continued throughout childhood and adulthood. Sun Exposure Adequate sensible sun exposure is an excellent source of vitamin D and should be recommended to all patients for both the treatment and prevention of vitamin D deficiency. Usually, exposure of the arms and legs (with sun protection on the face) for about 15 to 30 minutes (depends on degree of skin pigmentation, time of day, season, latitude, dust, and age of patient) between 10 a.m. and 3 pm at least twice a week is sufficient to stimulate cutaneous vitamin D production. Calcium and Phosphate Replacement Because inadequate calcium intake may contribute to vitamin D deficiency and patients do not usually meet daily calcium requirements from dietary sources alone, all patients should be given calcium supplementation. Phosphate supplementation is not usually necessary unless there is an acquired or inherited disorder causing phosphate wasting in the 34 Chapter 2: Disorders of Calcium and Bone Metabolism

kidneys, such as hypophosphatemic rickets or oncogenic osteomalacia. These patients require phosphate supplementation in addition to vitamin D replacement and vitamin D metabolite. Caution should be exercised when giving phosphate supplements, because high-dose phosphate multiple times a day causes a reduction in ionized calcium, resulting in an increase in parathyroid hormone production and tertiary hyperparathyroidism. Therefore, smaller doses of phosphate should be taken more frequently throughout the day to maintain a normal serum phosphate level without causing significant hyperparathyroidism. Dosing Recommendations The current recommendation from both the American Association of Pediatrics and the Lawson Wilkins Pediatric Endocrine Society is a minimum dietary intake of vitamine D is 400 international units/day (10 mcg /day) for neonates, children, and adolescents. If this amount cannot be achieved through their normal diet," vitamin D" supplement should be administered. Exclusively breastfed infants and those consuming less than one liter of infant formula per day should receive 400 international units per day of an oral liquid vitamin D product. Preterm infants should receive 400 to 800 international units of vitamin D (10 to 20 mcg) per day to compensate for decreased placental transfer in utero and decreased gastrointestinal absorption after birth. For treatment of documented vitamin D deficiency, infants to be given 1,000 to 2,000 international units per day (25 to 50 mcg) and older children may be given up to 5,000 international units per day (125 mcg) for 2 to 3 months. Vitamin D supplements taken with food may help to reduce stomach upset. Calcium supplementation (30 to 75 mg/kg/day oral elemental calcium) is often necessary initially to maximize response in patients with vitamin D deficiency. Patients receiving vitamin D supplementation should undergo periodic monitoring of serum 25(OH)D levels, serum calcium, phosphorus, and alkaline phosphatase at one and three months or until stabilized, followed by annual reassessment. Parathyroid and bone mineralization studies should be conducted as needed. Key Notes . There is a phenomenon called ―Hungry bone syndrome due to vitamin D therapy‖ which is the worsening of hypocalcaemia after the starting of vitamin D therapy for hypocalcaemia rickets may occur. So it Blueprint in Pediatric Endocrinology 35

is important to consider supplementing calcium during the first two weeks of therapy, to prevent the possibility of hypocalcaemia and seizures attributed to hungry bones . Untreated or neglected rickets can cause permanent bone deformity and lead to stunted growth. Surgical intervention may be necessary to repair severe bony abnormalities

Vitamin D–Dependent Rickets (type 1) This disorder results from a genetic deficiency in one- alpha hydroxylase enzyme that converts calcidiol to calcitriol in the kidney. It is inherited as an autosomal recessive, and the gene is located in band 12q13.3. Clinical and laboratory examination findings are similar to those associated with nutritional rickets, with low levels of 1, 25(OH) 2 vitamin D with normal values of 25- hydroxyl vitamin D3. These patients develop rickets despite receiving vitamin D at the recommended preventive doses.

Medical treatment consists of oral calcitriol (0.5-1.5 mcg/day) or one alpha (dose 1 mcg/day). These patients may also respond to supra pharmacologic doses of vitamin D (5,000-10,000 U/day).

Vitamin D-Resistant Rickets (Type II Vitamin D–Dependent Rickets) It is a rare autosomal recessive disorder, most often caused by mutations in the vitamin D receptor gene. It usually presents with rachitic changes not responsive to vitamin D treatment and the circulating levels of both 25 (OH) vitamin D-3 and 1,25 (OH)2 vitamin D-3 are elevated, differentiating it from vitamin D dependent rickets type I. Alopecia capitis or alopecia totalis is seen in some families with vitamin D- dependent rickets type 2. This is usually associated with a more severe phenotype. The clinical picture is evident early in life, and consists of rickets with very severe hypocalcaemia, although a variant without alopecia has been reported. Patients without alopecia appear to respond better to treatment with vitamin D metabolites. Serum levels of 1, 25(OH) 2 vitamin D3 are typically elevated. It can be lethal in the perinatal period. Several mutant forms of receptor defect rickets are 36 Chapter 2: Disorders of Calcium and Bone Metabolism

recognized, with a wide range of severity and response to calcitriol therapy.

Fig. (2-7): Showing Partial Hair Loss in Vitamin- D – Resistant Rickets. Patients are benefiting from continuous intravenous calcium through central line (400-1400 mg/m2/day) followed by oral therapy with high doses of calcium of 1000-3000 mg/m2/day (with secondary risk of nephrocalcinosis, hypercalciuria, nephrolithiasis, and cardiac arrhythmias). The use of continuous daily of calcium intravenous infusion / high oral dose of elemental calcium (some reported cases as high as 14 -to-20 gram per day) supplemented with oral phosphate is an effective method of treatment of vitamin D dependent rickets type II. . The treatment is more effective when is started early in the course of the disease and lead to early healing and better growth with prevention of bone deformities as well early treatment may also lead to improvement in alopecia, the mechanism for which needs to be elucidated.

Hypophosphatemic Rickets Hypophosphatemic rickets is less common than hypocalcemic rickets, although pediatrician should be aware of its occurrences, characterized by rickets associated with hypophosphatemia, resulting Blueprint in Pediatric Endocrinology 37

from dietary phosphorus deficiency or due to defects in renal tubular function; skeletal deformities are present but hypocalcaemia, myopathy, and tetany are absent and serum parathyroid hormone is normal. Several different familial and acquired conditions may lead to hypophosphatemia in children. Kidneys fail to reabsorb sufficient phosphate, leading to low levels of serum phosphate. This is usually evident only after age 6-10 months. Prior to this occurrence, the glomerular filtration rate is low, which sustains an adequate phosphate level. Once renal maturity is reached, phosphate levels are usually low. Levels of 1, 25(OH) 2 vitamin D are normal in these patients, which is actually an abnormal response to hypophosphatemia, in which levels of 1, 25(OH) 2 vitamin D should increase. Mutations of PHEX (phosphate regulating gene with homologies to endopeptidases on the X chromosome) and DMP1 (dentin matrix protein 1) result in X-linked hypophosphatemic rickets and autosomal recessive hypophosphatemic rickets, respectively. Most families of patients with familial hypophosphatemia exhibit an X-linked dominant inheritance. FGF-23 (fibroblast growth factor 23) has been implicated in the renal phosphate wasting in tumor-induced Osteomalacia and autosomal dominant hypophosphatemic rickets. Because calcium levels remain normal, neither tetany nor secondary hyperparathyroidism are present. Optimal therapy consists of oral phosphate in a dose of 40-60 mg/kg/day (1-2 mmol/kg/day) in 5 divided doses plus oral calcitriol (15- 25 ng/kg/day). Calcitriol (Rocaltrol) prevents increases in parathyroid hormone caused by phosphate therapy. Of note, phosphate half-life in serum is short, which usually causes low phosphate levels in fasting serum samples, despite proper therapy. Efficacy is reflected by proper linear growth. Minor changes in calcitriol dosage may produce hypercalcemia and renal damage. The calcium-creatinine (mg/mg) ratio in urine must be closely monitored at first and then every 3-6 months. An elevated phosphate intake may produce secondary hyperparathyroidism. Therefore, only experienced practitioners should treat that patients.Monitoring also includes clinical deformities as well for potential adverse effects to therapy which include nephrocalcinosis and hypertension. 38 Chapter 2: Disorders of Calcium and Bone Metabolism

The aim of management of these cases are, to maintain serum phosphate more than 1 mmol/l, to keep parathyroid hormone in normal range (avoidance of secondary hyperparathyroidism) and to improve catch up growth and in some cases additional of growth hormone therapy might benefiting the catch up of the growth. . Hypophosphatemic rickets is characterized by clinical rickets with short stature from an early age. . Characterised by low phosphate (<1 mmole/l) with elevated alkaline phosphatase (> 500 u/l) and an inappropriately low 1, 25 (OH) 2 Vitamin D. . Renal phosphate loss is high (low tubular reabsorption of phosphate). . In approximately 70%, mutations of the PHEX gene on the X chromosome are found.

Hypophosphatasia Is an autosomal recessive inherited disorder characterized by a deficiency of the tissue-nonspecific (liver, bone, and kidney) isoenzyme of alkaline phosphatase, increased urinary excretion of phosphorylethanolamine, and skeletal disease that includes osteomalacia and rickets. The severity of clinical expression is remarkably variable and spans intrauterine death from profound skeletal hypomineralization at one extreme to lifelong absence of symptoms at the other. As a consequence, six clinical disease types are distinguished. The age at which skeletal disease is initially noted delineates, in large part, the perinatal (lethal), infantile, childhood, and adult variants of the disorder. However, affected children and adults may manifest only the unique dental abnormalities of the syndrome and, accordingly, are classified as having odontohypophosphatasia. Finally, patients with the rare variant, pseudohypophosphatasia have the clinical, radiologic, and biochemical features of the classic disease without a decrease in the circulating levels of alkaline phosphatase. These individuals have defects in cellular localization and substrate specificity of the enzyme. Blueprint in Pediatric Endocrinology 39

Affected infants exhibit hypercalcemia, hypercalciuria, enlarged sutures of the skull, craniosynostosis, delayed dentition, enlarged epiphyses, and prominent costochondral junctions. Genu valgum or genu varum may develop subsequently. In older children, disease may be limited to rickets. Surprisingly, the disorder in adults is mild despite the presence of osteopenia. Indeed, the disease may be limited to slowly healing metatarsal fractures or loss or fracture of teeth. Nevertheless, 50% of patients have a history of early exfoliation of deciduous teeth and/or rickets, and disease may reflect re-expression of the childhood disorder. The perinatal and infantile forms of disease are inherited as autosomal recessive traits. The modes of inheritance for odontophosphatasia, adult hypophosphatasia, and childhood hypophosphatasia remain unclear, although an autosomal dominant disease transmission has been described in some kindred with mild or severe disease. Treatment of Hypophosphatasia Supportive treatment is important and may include craniotomy in children (to manage craniosynostosis) and, insertion of load-sharing intramedullary rods to treat fractures. Expert dental care is also crucial to minimize tooth loss and to prevent consequent malnutrition in youth.

Fig. (2-8): Showing Radiological Features of Hypophosphatesia. Drug-induced Rickets Chronic anticonvulsant therapy (particularly with Phenobarbital and phenytoin) may cause rickets, regardless of appropriate vitamin D intake. The main mechanism is related to induction of hepatic cytochrome P-450 hydroxylation, generating inactive metabolites. Levels of 25- hydroxyvitamin D3 were reported to be low in children on long-term anticonvulsant therapy. Fractures were associated with the use of 40 Chapter 2: Disorders of Calcium and Bone Metabolism

anticonvulsants in patients with cerebral palsy. A down regulation of 25- hydroxylation by phenobarbital may explain, at least in part, the increased risk of osteomalacia, bone loss, and fractures associated with long-term Phenobarbital therapy. Supplementation of 800-1000 IU/day, plus good calcium intake, may be sufficient. Fanconi's Syndrome Is a disease of the proximal renal tubules of the kidney in which glucose, amino acids, uric acid, phosphate and bicarbonate are passed into the urine, instead of being reabsorbed. It may be inherited, or caused by drugs or heavy metals. The loss of bicarbonate results in Type 2 or proximal renal tubular acidosis. The loss of phosphate results in the bone disease rickets (even with adequate vitamin D and calcium). The clinical features of proximal renal tubular acidosis include; polyuria, polydipsia and dehydration, hypophosphatemic rickets , growth failure, acidosis, hypokalemia, hyperchloremia, hypophosphatemia, phosphaturia, glycosuria, Proteinuria/ aminoaciduria and hyperuricosuria. Inherited causes include Cystinosis, which is the most common cause in children. Other recognized causes are Wilson's disease (a genetically inherited condition of copper metabolism), Lowe syndrome, tyrosinemia (Type I), galactosaemia, glycogen storage diseases, and fructose intolerance. Acquired causes include ingesting expired tetracycline, and as a side effect of tenofovir in cases of preexisting renal impairment. In the HIV population, most patients respond to a combination of managing the underlying cause when possible with fluid and bicarbonate replacements and vitamin D therapy. These patients do not necessarily appear to require treatment with calcitriol. Renal tubular acidosis, through phosphate wasting, may also cause rickets. McCune-Albright Syndrome Patients with this syndrome may have hypophosphatemia secondary to urinary phosphate leak, which may cause osteomalacia. Fasting phosphate levels should always be monitored in these patients, and phosphate supplements prescribed when indicated.

Blueprint in Pediatric Endocrinology 41

Renal Osteodystrophy (Renal Rickets) In end-stage renal disease, renal 1-hydroxylase is diminished or lost, and excretion of phosphate is defective. This leads to low levels of 1, 25(OH) 2 vitamin D, hypocalcaemia, and failure of osteoid calcification. Osteodystrophy (renal rickets) is the only type of rickets with a high serum phosphate level. It can be dynamic (a reduction in osteoblastic activity) or hyperdynamic (increased bone turnover). Treatment of these patients includes phosphate binders, a low phosphate intake, and calcitriol or one Alpha vitamin D. Hepatic Rickets

Fig. (2-9): Showing with Hepatic Rickets. Vitamin D is hydroxylated in the liver to form 25-hydroxyvitamin D; patients with severe parenchymal or obstructive hepatic disease may have reduced production of this metabolite. These patients rarely manifest biochemical or histological evidence of rickets. Indeed, an overt decrease of 25-hydroxyvitamin D generally requires concomitant nutritional deficiency or interruption of the enterohepatic circulation. Malabsorption Rickets Malabsorption of vitamin D is suggested by a history of liver or intestinal disease. Undiagnosed liver or intestinal disease should be 42 Chapter 2: Disorders of Calcium and Bone Metabolism

suspected if the child has gastrointestinal symptoms, although occasionally, rickets may be the presenting complaint. Fat malabsorption is often associated with diarrhea or oily stools, and there may be signs or symptoms suggestive of deficiencies of other fat-soluble vitamins (A, D, E, and K). Oncogenic Osteomalacia Is a paraneoplastic syndrome with hypophosphatemia secondary to decreased renal phosphate reabsorption, normal or low serum 1, 25- dihydroxyvitamin D concentration and osteomalacia. Several mesenchymal tumors of bone or connective tissue (e.g. fibroangioma, and giant cell tumors) secrete a phosphaturic substance (parathyroid like protein) that results in rickets. The age of onset has been late childhood, adolescence, or young adulthood. The clinical characteristics are similar to those associated with familial hypophosphatemia. FGF-23 causes renal phosphate wasting in tumor-induced osteomalacia. Treatment is surgical removal of the tumor (if it can be located), with excellent results. Key Points . Rickets is deficient mineralization at the growth plate of long bones, resulting in growth retardation. If the underlying condition is not treated, bone deformity occurs, typically causing bowed legs and thickening of the ends of long bones. . Only occurs in growing children before fusion of the epiphyses, typically affecting wrists, knees, and costochondral junctions. . Occurs primarily because of a nutritional deficiency of vitamin D, but can be associated with deficiencies of calcium or phosphorus. . Mainstay of treatment is to correct vitamin D deficiency and to ensure adequate calcium intake. . Can be prevented in many cases by ensuring that children and pregnant women have sufficient vitamin D and calcium intake. Hypoparathyroidism Parathyroid hormone (PTH) is an 84–amino acid polypeptide. Production and secretion of PTH are regulated by a G protein–coupled calcium-sensing receptor. PTH half-life is approximately 4 minutes. The net effects of PTH activity are an increase in serum calcium and a Blueprint in Pediatric Endocrinology 43

decrease in serum phosphate. PTH acts directly on bone to stimulate bone resorption and cause calcium and phosphate release. PTH acts directly on the kidney to decrease calcium clearance and to inhibit phosphate reabsorption. By stimulating renal 1-alpha-hydroxylase activity, PTH increases serum concentrations of 1, 25-dihydroxyvitamin D, the active form of vitamin D and, thus, indirectly stimulates calcium and phosphate absorption by the gut through the actions of vitamin D. The phosphaturic effect of PTH offsets the increases of serum phosphate driven by increased bone resorption and GI absorption. Hypoparathyroidism results in loss of the direct and indirect effects of PTH on bone, the kidney, and the gut. Calcium and phosphate release from bone is impaired, calcium absorption from the gut is limited, hypercalciuria develops despite hypocalcaemia, and retention of phosphate from the urine causes increased plasma phosphate levels. Various congenital or acquired disorders can lead to developmental failure of the parathyroid glands, failure of functional hormone production, or destruction of the glands. These disorders all manifest as hypocalcaemia, usually with hyperphosphatemia and undetectable or inappropriately low levels of circulating PTH. Hereditary hypoparathyroidism can occur as an isolated entity with a variable pattern of inheritance (idiopathic hypoparathyroidism), in association with defective development of thymus and the parathyroid glands (DiGeorge syndrome or bronchial dysgenesis), or as acquired autoimmune polyglandular syndrome. In addition to low or absent PTH and hypocalcaemia, certain skin manifestations, such as alopecia and candidiasis frequently occur. Causes of Hypoparathyroidism Hypoparathyroidism may be transient, genetically inherited, or acquired. Transient Hypoparathyroidism . Preterm and low birth neonates are at increased risk, and as many as 50% of them might have a deficient surge in PTH that results in hypocalcaemia. . In a group of infants with transient idiopathic hypocalcaemia (1–8 wk of age), serum levels of parathyroid hormone (PTH) are significantly 44 Chapter 2: Disorders of Calcium and Bone Metabolism

lower than those in normal infants. It is possible that the functional immaturity is a manifestation of a delay in development of the enzymes that convert glandular PTH to secreted PTH; other mechanisms are possible. . These infants may be born prematurely, which is a risk factor for insufficient PTH response. They may have hypomagnesaemia from maternal magnesuria complicating glucosuria. Low serum magnesium can impair PTH release and action. . Maternal hypercalcemia from hyperparathyroidism can also cause prolonged suppression of PTH secretion in the neonate. Permanent Hypoparathyroidism . DiGeorge syndrome (hypoparathyroidism, absence of thymus gland with T-cell abnormalities, and cardiac anomalies) is associated with abnormal development of the third and fourth pharyngeal pouches from which the parathyroids derive embryologically and represents an example of a defect in parathyroid gland development. DiGeorge syndrome and velocardiofacial syndrome are variants of the chromosome arm 22q11 microdeletion syndrome. Several cases of chromosome 10p deletion have also been reported in which affected individuals have some features of DiGeorge syndrome. . X-linked recessive hypoparathyroidism has been associated with parathyroid agenesis and has been mapped to chromosome arm Xq26- q27, the location of a putative developmental gene. . Familial cases of hypoparathyroidism due to mutations of the PTH gene located on chromosome arm 11p15 have been identified. These mutations have been both dominantly and recessively inherited. . The hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is associated with partial monosomy of chromosome arm 10p. . Mitochondrial cytopathies, such as Kearns-Sayre syndrome (external ophthalmoplegia, ataxia, sensorineural deafness, heart block, and elevated cerebral spinal fluid protein), are associated with hypoparathyroidism. Blueprint in Pediatric Endocrinology 45

Fig. (2-10): Showing two Affected Brothers with Sanjad-Sakati Syndrome). . Autosomal dominant and sporadic gain-of-function mutations of the Calcium sensing receptor, a G-protein coupled receptor, cause hypocalcemic hypercalciuria by lowering the serum calcium concentration that is required for PTH secretion and urinary calcium reabsorption. Individuals with Calcium receptor mutations have PTH concentrations that are within the reference range in the setting of hypocalcaemia; they can be asymptomatic or severely affected. These individuals must be differentiated from individuals with true hypoparathyroidism because treatment with active vitamin D (calcitriol) can cause nephrocalcinosis and renal insufficiency by exacerbating the already high urinary calcium excretion. Therapy with Calcitriol should be restricted to symptomatic individuals and should be sufficient enough to 46 Chapter 2: Disorders of Calcium and Bone Metabolism

relieve symptoms without normalizing serum calcium concentrations. Treatment with hydrochlorothiazide has been shown to be beneficial. In addition, PTH therapy could be effective in correcting serum and urine calcium and the phosphate levels in this disorder. . Sanjad Sakati syndrome (SSS) is an autosomal recessive disorder found exclusively in people of Arabian origin. It was first reported from the Kingdom of Saudi Arabia in 1988 as a newly described syndrome mainly from the Middle East and the Arabian Gulf countries. Children affected with this condition are born small for gestational age and present with hypocalcemic tetany or seizures due to hypoparathyroidism at an early stage in their lives. They have typical physical features, namely; long narrow face, deep set small eyes, beaked nose, large floppy ears, micrognathia, severe failure to grow both intrauterine and extra uterine and mild to moderate mental retardation. Acquired Hypoparathyroidism . Hypoparathyroidism incurred during neck surgery may be transient or permanent depending upon the extent of injury and preservation of the parathyroid glands. The risk varies depending on the series and experience of the surgeon. Parathyroid autotransplantation can be used to preserve parathyroid function. . Hypoparathyroidism following months of radioactive iodine ablation of the thyroid has been described as more common in treatment of Grave disease than with treatment of thyroid cancer. Radiation to the chest or neck area for cancer is also associated with hypoparathyroidism. . Parathyroid gland destruction due to iron deposition (hemosiderosis) or copper deposition (Wilson's disease). . Autoimmune polyendocrinopathy syndrome, type 1, which is a very rare autoimmune disorder characterized by autoimmune polyendocrinopathy (APS). The 3 major components are chronic mucocutaneous candidiasis, hypoparathyroidism, and autoimmune adrenal insufficiency. The presence of all 3 components is not required to make a diagnosis; at least two components have to be present in an individual. Additional manifestations, including, type 1 diabetes, hypogonadism, pernicious anemia, malabsorption, alopecia, and vitiligo, may be present as well. The first manifestation usually occurs in childhood, and the complete evolution of the 3 main diseases takes place Blueprint in Pediatric Endocrinology 47

within the first 20 years of life. Accompanying diseases continue to appear at least until the fifth decade of life. Candidiasis usually is the first clinical manifestation, most often presenting in people younger than 5 years. Hypoparathyroidism occurs next, usually in people younger than 10 years. Lastly, Addison disease occurs in people younger than 15 years. Laboratory Studies . Total and ionized serum calcium levels are low. Ionized serum calcium level should be evaluated when patient has low protein or albumin in the blood. . Serum phosphate levels are elevated in hypoparathyroidism, although they can be within the reference range, especially in the infant without enteral feeding and low phosphate/protein intake. . Serum magnesium levels are obtained to rule out hypomagnesaemia as a cause of hypoparathyroidism. In this condition, hypocalcaemia could be corrected very rapidly with magnesium therapy. In general, magnesium levels are within the reference range in hypoparathyroidism and PHP. . Intact parathyroid hormone (iPTH) should be obtained at the time of hypocalcaemia. Nomograms have been developed for the interpretation of serum iPTH concentration with respect serum calcium. . BUN and creatinine concentrations are normal in hypoparathyroidism. . 25-Hydroxyvitamin D level is within the reference range in hypoparathyroidism. 1, 25-Dihydroxyvitamin D level is expected to be low in hypoparathyroidism because of lack of PTH-stimulated 1-alpha- hydroxylase activity. . Urine calcium to creatinine ratio is elevated in PTH-deficient states and particularly elevated in calcium-sensing receptor mutations. . Thyroid studies and thyroid antibodies, if an autoimmune process is suspected. . Adrenocorticotropic hormone and adrenal antibodies, if an autoimmune process is suspected, concomitant primary adrenal 48 Chapter 2: Disorders of Calcium and Bone Metabolism

insufficiency can be revealed by an elevated ACTH level, and adrenal antibodies may be present. Imaging Studies . Chest radiography to look for thymic aplasia which is associated with 22q11 deletion syndrome and can be assessed with chest radiography. . Echocardiography to be done for an infant with a murmur and in whom hypoparathyroidism is suggested to assess for conotruncal lesions that are associated with the 22q11 deletion syndrome. . Renal ultrasonography as treatment of hypoparathyroidism can lead to nephrocalcinosis as a result of hypercalciuria. Baseline renal ultrasonography with initial treatment should be performed. Treatment of Hypoparathyroidism The initial dosage of calcitriol is 0.25 μg / day; the maintenance dosage ranges from 0.01–0.10 μg /kg /day to a maximum of 1–2 μg/day. Calcitriol has a short half-life and should be given in 2 equal divided doses; it has the advantages of rapid onset of effect (1–4 days) and rapid reversal of hypercalcemia after discontinuation in the event of over dosage (calcium levels begin to fall in 3–4 days). One - alpha hydroxycholecalciferol dose of 25-50 ng / kg/day (maximum 1 mcg / day). An adequate intake of calcium should be ensured. Supplemental calcium can be given in the form of calcium gluconate or calcium glubionate to provide 800 mg of elemental calcium daily, but it is rarely essential. Foods with high phosphorus content such as milk, eggs, and cheese should be reduced in the diet. Complications of Hypoparathyroidism . Nephrocalcinosis . Hypocalcaemia-related events, including tetany, seizure, laryngospasm, arrhythmia, and syncope Pseudohypoparathyroidism (PHP) In 1942, Fuller Albright first described & introduced the term pseudohypoparathyroidism to describe patients who presented with PTH- resistant hypocalcaemia and hyperphosphatemia along with an unusual Blueprint in Pediatric Endocrinology 49

constellation of developmental and skeletal defects, collectively termed Albright hereditary Osteodystrophy (AHO). These features include short stature, rounded face, shortened fourth metacarpals and other bones of the hands and feet, obesity, dental hypoplasia, and soft-tissue calcifications/ossifications. (See image below.) In addition, administration of PTH failed to produce the expected phosphaturia or to stimulate renal production of cyclic adenosine monophosphate (cAMP). PHP is a heterogeneous group of disorders characterized by hypocalcaemia, hyperphosphatemia, increased serum concentration of parathyroid hormone (PTH), and insensitivity to the biological activity of PTH. Peripheral tissue resistance to PTH was classically termed pseudohypoparathyroidism (PHP).

Fig. (2-11): Showing Short Metacarpal in Patients With Pseudohypoparathyroidism. The characteristic biochemical manifestations are hypocalcaemia and hyperphosphatemia, just as in hypoparathyroidism; however, circulating levels of PTH are elevated, rather than low or undetectable. The renal tubule is the primary site of PTH resistance, although variable degrees of skeletal resistance have also been reported. When the skeleton retains sensitivity to PTH, lesions characteristic of hyperparathyroidism, including osteitis fibrosa cystica, can develop. PTH stimulates renal cyclic adenosine monophosphate (cAMP) production, and levels of cAMP increase in the urine following administration of the hormone. A direct correlation has been demonstrated between the degree of PTH resistance (as assessed by the magnitude of the change in cAMP 50 Chapter 2: Disorders of Calcium and Bone Metabolism

excretion or renal phosphate threshold) and the ambient circulating PTH level. The renal cAMP response is the basis of a diagnostic test that allows partial classification of this heterogeneous group of disorders. Individuals with PHP who demonstrate a blunted urinary cAMP response have type 1 PHP. Those who generate a normal cAMP response have type 2 PHP. Several variants of PHP have been identified, and PHP type 1a is the best understood form of the disease. The molecular defects in the gene (GNAS1) encoding the alpha subunit of the stimulatory G protein (Gsa) contribute to at least 3 different forms of the disease: PHP type 1a, PHP type 1b, and pseudopseudohypoparathyroidism. All patients are heterozygous, with one normal Gsa allele; the mutant allele leads to production of inactive Gsa or to small amounts of active Gsa. Several other peptide hormones, including thyroid-stimulating hormone (thyrotropin), antidiuretic hormone, the gonadotropin, glucagon, adrenocorticotropin, and growth hormone–releasing hormone, use the alpha subunit of stimulatory G protein to enhance cAMP production. Patients with PHP type 1a can present with resistance to the effects of any of these hormones. Patients with PHP type 1b lack features of AHO, have normal expression of Gsa protein in accessible tissues, and manifest hormonal resistance limited to PTH target tissues. PTH resistance may be limited to the kidney, with PTH responsiveness preserved in the bone, as evidenced by the hyperparathyroid skeletal lesions observed in these patients. PHP type 1c and PHP type 2 are much less characterized than the other forms of PHP. Patients with PHP type 1c do not have a detectable defect in Gsa protein despite having clinical and laboratory findings similar to those observed in patients with PHP type 1a. Patients with PHP type 2 shows no skeletal and developmental defects, similar to patients with PHP type 1b, but they show a normal urinary cAMP response, in contrast to patients with PHP type 1b. Pseudopseudohypoparathyroidism Patients with pseudo-PHP have the phenotype of AHO but with normal biochemical parameters. Patients with pseudo-PHP are often found in the same kindred as those with PHP type 1a. Blueprint in Pediatric Endocrinology 51

Clinical Features Patients with PHP can present in infancy, especially if significant hypocalcaemia occurs. Some forms of PHP may remain unnoticed or undiagnosed if patients do not have hypocalcaemia and /or features of AHO. Patients with PHP type 1a present with a characteristic phenotype, collectively called AHO. The constellation of findings includes short stature, stocky habitus, and obesity, developmental delay, round face, dental hypoplasia, brachymetacarpal, brachymetatarsal, and soft tissue calcification/ossification. Hypocalcaemia in children or adolescents are often asymptomatic. Patients may develop paresthesia, muscular cramping, tetany, carpopedal spasm, or seizure. Primary hypothyroidism occurs in most patients with PHP type 1a. Reproductive dysfunction commonly occurs in persons with PHP type 1a. Women may have delayed puberty, oligomenorrhoea, and infertility. Features of hypogonadism may be less obvious in men. Testes may show evidence of maturation arrest or may fail to descend normally. Fertility appears to be decreased in men with PHP type 1a. Within the spectrum of PHP type 1a, variability exists in osteoclast responsiveness to PTH. Some patients may have osteopenia and rickets. Mentation is impaired in approximately half of patients with PHP type 1a and appears to be related to the Gsa deficiency rather than to chronic hypocalcaemia because patients with other forms of PHP and hypocalcaemia have normal mentation. Physical examination may reveal signs of hypocalcaemia, including positive Chvostek‘s sign (twitching of facial muscles after tapping the facial nerve just in front of the ear) and/or Trousseau sign (carpal spasm after maintaining an arm blood pressure cuff at 20 mm Hg above the patient's systolic blood pressure for 3 min). Occasionally, cataracts or papilledema are present. Patients with PHP type 1b present with hypocalcaemia without AHO. The severity of hypocalcaemia can vary greatly among family members of the same kindred. Molecular defects in the GNAS1 gene, which encodes Gsa, contribute to at least 3 different forms of the disease: PHP type 1a, PHP type 1b, and pseudo-PHP. Laboratory Studies . Measurement of serum total calcium and ionized calcium) to confirm hypocalcemic state. Serum phosphate levels are elevated. 52 Chapter 2: Disorders of Calcium and Bone Metabolism

. Determination of the serum concentration of intact PTH, when the serum concentration of PTH in a hypocalcemic patient is increased, the patient has either a form of PHP or secondary hyperparathyroidism. . Assessment of skeletal and renal responsiveness to PTH: by measurement of changes in serum calcium, phosphorus, cAMP, and calcitriol concentrations and in urinary cAMP and phosphorus excretion after administration of the biosynthetic PTH. . Thyroid function tests and measurement of gonadotropin and testosterone or estrogen levels, in addition to growth hormone function assessed by insulin like growth factor-1. Imaging Studies . Radiography of the hand may show a specific pattern of shortening of the bones in which the distal phalanx of the thumb and the third through fifth metacarpals are shortened most severely. Radiography may also show small soft tissue opacities (calcifications / ossifications).

Fig. (2-12): Showing Subcutaneous Calcifications. Blueprint in Pediatric Endocrinology 53

Fig. (2-13): CT scanning may reveal calcification of the basal ganglia. . An electrocardiogram may reveal prolongation of the QT interval secondary to hypocalcaemia. . Analysis of the GNAS1 gene helps identify the specific genetic defect in patients with PHP type 1a. . Patients with PHP type 1b may be evaluated for parathyroid- related bone disease. Consider bone mineral density (BMD) testing in this group of patients. Treatment of Pseudohypoparathyroidism All patients with severe symptomatic hypocalcaemia should be initially treated with intravenous calcium. Administration of oral calcium and one-alpha-hydroxylated vitamin D metabolites remains the mainstay of treatment and should be initiated in every patient with a diagnosis of PHP (doses are the same as in cases of hypoparathyroidism).

The goals of therapy are to maintain serum total and ionized calcium levels within the reference range to avoid hypercalciuria and to suppress PTH levels to normal. This is important because elevated PTH levels in patients with PHP could cause increased bone remodeling and can lead to hyperparathyroid bone disease. Monitor therapy through regular serum 54 Chapter 2: Disorders of Calcium and Bone Metabolism

and urine calcium measurements. Exercise caution to avoid renal or hypercalcemic complications. Monitor serum PTH levels with a goal of maintaining serum PTH levels within the reference range. Hypomagnesaemia Magnesium is an important cofactor for PTH secretion. Hypocalcaemia associated with hypomagnesaemia is associated with both deficient PTH release from the parathyroid glands and impaired responsiveness to the hormone. In severe cases of hypomagnesaemia (serum level <1 mg/dl), suppressed parathyroid secretion can occur. Resistance to the actions of PTH at the level of bone and kidney may also contribute to the hypocalcaemia and replenishment of magnesium stores promptly restores parathyroid function to normal. Treatment Severe hypomagnesemia is initially treated with intramuscular injection of magnesium sulfate, 0.2 ml/kg of 20% solution repeated at 6- hour intervals. Long-term treatment requires oral magnesium supplementation with Mg chloride, citrate, or lactate in a dose of 24 to 48 mg/kg/day in four divided doses up to a maximum of 1 g magnesium per day. Hypercalcemia in Children Hypercalcemia in children is not a common phenomenon and symptoms of hypercalcemia are dependent on both the serum level of calcium and the rate of rise. Mild hypercalcemia defined as serum total calcium of (<12 mg / dl, 3 mmole/l), patients are usually asymptomatic. Those with moderate hypercalcemia levels of (12.0 to 13.5 mg / dl, 3.0 to 3.4 mmole/l); usually have weakness, anorexia, constipation, polyuria and polydipsia. Severe Hypercalcemia (>13.5 mg / dl, > 3.5 mmole/l) can manifest as a life-threatening metabolic emergency with cardiac and central nervous system effects including encephalopathy, seizure, and coma. Causes of Hypercalcemia in Infants . Transient neonatal hyperparathyroidism has occurred in a few infants born to mothers with hypoparathyroidism or with pseudohypoparathyroidism. In each case, the maternal disorder had been undiagnosed or inadequately treated during pregnancy. The cause of the Blueprint in Pediatric Endocrinology 55

condition is chronic intrauterine exposure to hypocalcaemia with resultant hyperplasia of the fetal parathyroid glands. In the newborn, manifestations involve the bones primarily and healing occurs between 4 and 7 months of age. . Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant heterozygous mutation of the same calcium receptor-sensing gene (CASR) that is abnormal in the homozygous state in neonatal primary hyperparathyroidism. Patients have a tendency to elevated plasma levels of magnesium and hypocalciuria, but neither of these features can differentiate FHH from other forms of primary hyperparathyroidism with absolute certainty. The fractional clearance of calcium (ratio of calcium clearance to creatinine clearance, FeCa) is usually less than 0.01 in FHH, whereas a FeCa above 0.01 is a typical finding in other forms of primary hyperparathyroidism. The plasma level of calcitriol in FBHH is usually in the midnormal range in contrast to a tendency to elevated levels in primary hyperparathyroidism. . Subcutaneous fat necrosis, which manifests in neonate as violaceous plaques or nodules overlying fatty areas, can lead to life- threatening hypercalcemia at age 1-6 months. It is likely mediated by prostaglandin E or due to macrophage production of 1, 25- dihydroxyvitamin D. Treatment includes corticosteroids and symptomatic support of patient. . William‘s syndrome, which is associated with a deletion of elastin genes on chromosome 7, occurs as transient neonatal hypercalcemia, perhaps secondary to increased sensitivity to vitamin D. The syndrome is associated with characteristic elfin facies, mental retardation, and supravalvar aortic stenosis. Generally, hypercalcemia is symptomatic, with poor feeding and constipation, and spontaneously remits by age 9- 18 months. 56 Chapter 2: Disorders of Calcium and Bone Metabolism

Fig. (2-14): Showing Clinical Features of William’s Syndrome. . Idiopathic infantile hypercalcemia is a poorly understood disorder possibly related to non–malignancy-associated PTH-related protein (PTHrP), which spontaneously resolves by age 12 months. . Blue diaper syndrome is a selective defect in the intestinal transport of tryptophan. . Jansen metaphyseal chondrodysplasia is a rare disease of endochondral bone formation characterized by short stature, leg bowing, short-limbed dwarfism, and a waddling gait. Neonatally, these children appear normal but have radiographic and laboratory abnormalities. In early childhood, the external changes become more obvious. The condition arises from an activating mutation in the PTH/ PTHrP receptor. . Tertiary hyperparathyroidism occurs following prolonged secondary hyperparathyroidism. It is characterized by autonomous parathyroid activity (the ability of the parathyroid gland to act independently) causing hypercalcemia. This condition is most commonly seen in people who have been receiving maintenance dialysis or after renal transplantation.

Blueprint in Pediatric Endocrinology 57

Causes of Hypercalcemia in Children . Primary hyperparathyroidism (PHPT) in childhood is rare with an estimated incidence of around 2-5 / 100,000. It is most often sporadic and caused by a parathyroid adenoma. However, it may also occur due to hyperplasia of glands, especially in multiple endocrine neoplasias (MEN)-I and II syndromes. Multiple endocrine neoplasia (MEN) type I (Wermer syndrome) is rare autosomal dominant constellation of hyperparathyroidism, pancreatic tumors, and pituitary tumors treated by subtotal parathyroidectomy. Molecular diagnosis is now available for (MEN)-I and II. . Inactivation mutations of a CaSR gene cause familial hypocalciuric hypercalcemia (FHH) (also known as Familial Benign Hypercalcemia) because it is generally asymptomatic and does not require treatment when present in heterozygote. Patients who are homozygous for CaSR inactivating mutations have more severe hypercalcemia. . Thyrotoxicosis can cause sufficient bone resorption to increase serum calcium in 20% of cases. In these patients, thyrotoxicosis can also decrease serum PTH and increase urine excretion of cAMP and calcium. Although hypercalcemia is rarely subjectively symptomatic to the patient, it can lead to nephrocalcinosis and renal failure. This condition is rare in childhood, but it is possible in neonates of mothers with Graves‘s disease or in older children who develop Graves‘s disease. . Granulomatous disease, including sarcoidosis, tuberculosis, and Wegener disease may cause hypercalcemia via overproduction of 1, 25- dihydroxyvitamin D by macrophages and increased extra renal alpha1- hydroxylase activity. . Adrenal insufficiency can decrease the renal clearance of calcium. . Hypercalcemia may appear in the oliguric phase of acute renal failure due to the PTH increase stimulated by hyperphosphatemia. Also, children with renal failure treated with calcitriol for secondary hyperparathyroidism can develop a mild hypercalcemia. . Vitamin A in high doses, such as those found in retinoid therapy for acne, can directly stimulate bone resorption by functioning as a transcription factor in osteoclast stimulation. 58 Chapter 2: Disorders of Calcium and Bone Metabolism

. Thiazide diuretics may cause hypercalcemia because of their action on the distal tubule. . Milk-alkali syndrome (Burnett syndrome) from exogenous ingestion of calcium-containing antacids leads to renal insufficiency and metastatic calcinosis with increased phosphorus levels, increased levels of 1,25-dihyroxyvitamin D, decreased PTH levels, normal levels of serum alkaline phosphatase, normal urine calcium levels, and decreased urine phosphate levels. If continued over time, this may lead to Osteomalacia. This condition is particularly sensitive to the development of hypocalcaemia following treatment with Bisphosphonate therapy. . Immobilization can cause hypercalcemia. . Total parenteral nutrition may cause hypercalcemia. . Excessive supplementation of calcium. . Vitamin D intoxication due to ingestion of large doses of vitamin D can cause hypercalcemia, even in the absence of a markedly elevated 1, 25-dihydroxyvitamin D. . Vitamin-D receptor modulators (e.g., paricalcitol) are newer medications used to treat malignancy and hyperparathyroidism, which can increase serum calcium levels. Oncogenic Hypercalcemia . Primarily in leukemia, PTHrP increases osteoclast resorption of bone, renal reabsorption of calcium, and renal loss of phosphorous, leading to decreased serum phosphate levels, increased urinary cAMP, and detectable PTHrP. . Burkitt lymphoma and multiple myeloma, as well as bony tumors or sarcomas with bony metastases, can cause cytokine-mediated bone resorption. . Hodgkin and non-Hodgkin lymphoma may cause increased intestinal absorption of calcium via production of 1, 25-dihydroxyvitamin D by macrophages, which contain 1-alpha-hydroxylase activity, and may maintain a normal serum phosphorus level.

Blueprint in Pediatric Endocrinology 59

Clinical Manifestations of Hypercalcemia At all ages, the clinical manifestations of hypercalcemia of any cause include muscular weakness, fatigue, headache, anorexia, abdominal pain, nausea, vomiting, constipation, polydipsia, polyuria, loss of weight, and fever. When hypercalcemia is of long duration, calcium may be deposited in the renal parenchyma (nephrocalcinosis), with progressively diminished renal function. Renal calculi may occur and may produce renal colic and hematuria. Abdominal pain is occasionally prominent and may be associated with acute pancreatitis. Parathyroid crisis may occur, manifested by serum calcium levels greater than 15 mg/dl (> 3.5 mmole/l) progressive oliguria, azotaemia, stupor, and coma. In infants, failure to thrive, poor feeding, and hypotonia are common. Mental retardation, convulsions, and blindness may occur as sequelae of long- standing hypercalcemia. Laboratory Studies . In the neonate, corrected total calcium, phosphate, and parathyroid hormone (PTH) levels as well as the levels of maternal calcium and maternal PTH. Serum calcium levels from other family members may also be helpful. In the situation of inappropriately normal or high PTH, consider hyperparathyroidism, familial hypocalciuric hypercalcemia, and secondary hyperparathyroidism. When PTH is suppressed, malignancy, granulomatous disease, iatrogenic causes, adrenal insufficiency, thyrotoxicosis, and vitamin D intoxication are possibilities. . Serum electrolytes may be abnormal include sodium, potassium, and magnesium measurements. The reabsorption of these electrolytes is decreased in the proximal tubule, lowering their serum levels. . BUN and creatinine tests to evaluate renal function. . Pancreatic enzyme tests to evaluate for pancreatitis, and stool hemoccult tests to evaluate for gastritis or a peptic ulcer if symptoms point toward these possibilities. . High PTH levels usually indicate primary hyperparathyroidism if the urine calcium–to–creatinine ratio is high and indicates familial hypocalciuric hypercalcemia if the urine calcium–to–creatinine ratio is low (confirm with DNA sequence analysis for CASR gene). 60 Chapter 2: Disorders of Calcium and Bone Metabolism

. Low PTH levels usually indicate hypervitaminosis D if 25- hydroxyvitamin D and 1, 25-dihydroxyvitamin D levels are high and indicate malignancy if they are low (confirm with high PTHrP level). Imaging Studies . Plain radiography may reveal demineralization, pathologic fractures, bone cysts, and bony metastases. . Renal imaging, ultrasonography, CT urography, or intravenous pyelography (IVP) may reveal evidence of calcifications or stones. . Perform ultrasonography of the parathyroid glands if hyperplasia or adenoma is a primary diagnosis. A sestamibi nuclear scan may be helpful in locating a parathyroid adenoma. Treatment of Hypercalcemia . Initial treatment of hypercalcemia involves hydration to improve urinary calcium output. Isotonic sodium chloride solution is used, because increasing sodium excretion increases calcium excretion. Addition of a loop diuretic inhibits tubular reabsorption of calcium, with Furosemide having been used up to every 2 hours. Attention should be paid to other electrolytes (e.g., magnesium and potassium) during saline diuresis. These treatments work within hours and can lower serum calcium levels by 1-3 mg/dl within a day. For neonates, specifically, 5% dextrose in one-half isotonic sodium chloride solution with 30 meq/l potassium chloride at 2 times the maintenance dose along with 2-3 mg/kg/day of Furosemide and adequate phosphate supplementation to maintain normal levels. . Bisphosphonate serve to block bone resorption over the next 24- 48 hours by absorbance into the hydroxyapatite and by shortening the life span of osteoclast. Administered intravenously, they decrease serum calcium in 2-4 days with a nadir at 4-7 days. These medications have established safety and efficacy in children. . Calcitonin at subcutaneous or intramuscular doses of 3-6 mcg/kg every 6 hours, works within hours to decrease skeletal reabsorption of calcium and inhibit renal reabsorption, but it lowers serum calcium concentration only for 2-3 days because of tachyphylaxis. It can be expected to lower serum calcium only 0.5 mmole/l. adverse effects Blueprint in Pediatric Endocrinology 61

include nausea, cramping, abdominal pain, and flushing. One benefit of Calcitonin is that it has analgesic properties. . Corticosteroids are helpful in certain disorders, particularly malignancy-associated hypercalcemia, granulomatous disease, or vitamin D ingestion; and they can be given either IV or orally as prednisone in doses of 40-60 mg/m2/day or 1-2 mg/kg/day to inhibit osteoclast action and decrease intestinal calcium absorption. . Peritoneal dialysis or haemodialysis can be used in extreme situations, particularly in patients with renal failure; careful attention must be given to the phosphorus level following dialysis. . Cinacalcet hydrochloride (Sensipar) is the first medication approved from the calcimimetic class. . It changes the configuration of the transmembranal calcium- sensing receptor in a manner that makes it more sensitive to serum calcium. . It is primarily indicated for chronic renal disease and secondary hyperparathyroidism. . No large pediatric studies have been done to date, but its efficacy has been substantiated in adults.

Surgical Therapy . In patients with primary hyperparathyroidism, subtotal or total parathyroidectomy is the most common choice for children, depending on the number of glands involved with tumors. Parathyroidectomy can result in reference range serum calcium levels, an increase in bone mineral density, and successful prevention of kidney stones. . In patients with uremia, subtotal or total parathyroidectomy is an option when medical management with calcitriol or one of its analogs is unsuccessful or when tertiary hyperparathyroidism that is independent of external feedback develops. Citeria that favor parathyroidectomy in patients with mild or asymptomatic disease: . Serum calcium > 1 mg / dl above normal 62 Chapter 2: Disorders of Calcium and Bone Metabolism

. Kidney stone or extreme hypercalciuria (24 hour urine calcium > 400 mg / day) . Creatinine clearance reduced by 30% compared to age-matched normal individuals . Reduced bone density compared to peak bone mass (Z score < −2.5 SDS) at hip, lumbar spine or distal radius . Patients for whom medical surveillance is neither desirable nor possible (eg, patients for whom serial monitoring is impractical or unacceptable) Postoperative complications include transient hypocalcaemia because the parathyroid glands regain their sensitivity to circulating calcium. Hungry bone syndrome, a prolonged period of hypocalcaemia, can occur postoperatively in those cases of primary hyperparathyroidism that demonstrated significant bone demineralization. Bones reaccumulate calcium at the expense of circulating levels. Finally, as in thyroid surgery, a risk of damage to the recurrent laryngeal nerve resulting in permanent hoarseness of the voice is observed. Complications Complications of primary hyperparathyroidism are consequences of hypercalcemia, such as nephrolithiasis, dehydration, and cardiac arrhythmias. Complications of secondary untreated hyperparathyroidism are mainly skeletal and involve fractures, decreased bone density, bone pain, and muscle weakness. Key points . Symptoms of hypercalcemia include fatigue, muscle weakness, myalgia, depression, decreased mental concentration, headache, vague abdominal pain, and constipation. . An acute rise in the serum calcium level is more typically found in hypercalcemia of malignancy associated with accelerated bone resorption. . Severe hypercalcemia may include symptoms such as polyuria, polydipsia, nephrolithiasis, bone pain, and cardiac arrhythmias . Primary hyperparathyroidism may be asymptomatic, mild hypercalcemia incidentally found on a screening test of serum electrolytes may not be diagnostically pursued. Blueprint in Pediatric Endocrinology 63

. Failure to repeat the serum calcium determination and obtain serum intact parathyroid hormone (PTH) concentration to detect consistent elevation of serum calcium concentration in the face of elevated serum levels of intact PTH results in failure to diagnose the condition as primary hyperparathyroidism. . Treatment composed of hydration which is the mainstay of treatment; that enhances calciuria. Furosemide may be used with caution if adequate hydration. Hydrocortisone (1 mg/kg/ day divided into 4 doses), reduces intestinal absorption of calcium. Calcitonin transiently opposes bone resorption. In severe hypercalcemia, bisphosphonate may be considered. Surgical removal of parathyroid glands (may result in hypoparathyroidism). Osteoporosis in Children & Adolescence Osteoporosis is being increasingly recognized in pediatric practice. Bone volume is diminished and the incidence of fractures is greatly increased in this condition. In contrast to osteomalacia, which shows under mineralization and normal bone volume, histological sections of bone in all forms of osteoporosis reveal a normal degree of mineralization but a reduction in the volume of bone, especially trabecular bone (vertebral bone). In osteoporosis, by definition, there is also a reduced amount of bone tissue, (termed osteopenia) which is associated with non traumatic (pathological) fractures. Fractures as a consequence of osteoporosis can cause considerable pain and disability with a potential loss of independence for the child and significant disruption to school attendance and family life. There are many childhood conditions in which osteopenia assessing bone density by DXA scan. It is important to distinguish between osteopenia and osteomalacia as osteomalacia is caused by a reduction in mineralized bone matrix often secondary to vitamin D deficiency. Osteoporosis in children may be primary or secondary. . BMC or BMD Z score of more than 2 SDs below expected (less than −2) should be labeled ―low for age.‖ . Guidelines suggested that the diagnosis of osteoporosis in children be made only when both low bone mass (BMC or BMD z scores of less than −2) and a clinically significant fracture history (defined previously) are present 64 Chapter 2: Disorders of Calcium and Bone Metabolism

Primary Osteoporosis Primary osteoporosis can be divided into heritable disorders of connective tissue, including Osteogenesis imperfecta, Ehlers-Danlos syndrome, Marfan's syndrome, homocystinuria, and idiopathic juvenile osteoporosis. Secondary forms of osteoporosis include various neuromuscular disorders, chronic illness, endocrine disorders, drug- induced and inborn errors of metabolism (e.g. Gaucher's disease). when no obvious primary or secondary cause can be detected, idiopathic juvenile osteoporosis should be considered, especially if the following clinical features are evident: onset prior to puberty, long bone and lower back pain, vertebral fractures, long bone and metatarsal fractures, a washed-out appearance of the spine and appendicular skeleton, and improvement after puberty. Trabecular bones such as the spine and metatarsals are particularly affected by traumatic fractures. In general, calcium, phosphate, vitamin D metabolites, alkaline phosphatase, and parathyroid hormone are normal. Evaluation of bone mineral content and bone density by dual-energy x-ray absorptiometry or less often quantitative CT shows markedly reduced values. Osteogenesis Imperfecta (OI) Osteogenesis imperfecta is the most common genetic cause of osteoporosis and generalized disorder of connective tissue. The spectrum of OI is extremely broad, ranging from a form that is lethal in the perinatal period to a mild form in which the diagnosis may be equivocal in an adult. There is an underlying abnormality in bone matrix composition usually as the result of defective synthesis of type 1 collagen. It has an estimated incidence world wide of 1 in 10,000–20,000 births. In addition to evidence of low trauma fractures affected individuals often have evidence of joint hypermobility, easy bruising, flat feet and a blue sclera hue. The original classification on the basis of phenotypic features by "David Silence" consisted of four types varying in severity. Type I (mild form), is the most frequent form encountered and its characteristics include recurrent fractures in childhood with a reduction in fracture risk in adolescence, blue sclera, healing of fractures without residual deformity and the variable presence of abnormalities of tooth composition, dentinogenesis imperfecta. Type II is the most severe form with multiple fractures present in utero or at birth, often associated with respiratory distress caused by chest deformity. Such infants usually Blueprint in Pediatric Endocrinology 65

do not survive the neonatal period. Type III is another severe type with multiple fractures present at birth or early life. Such fractures usually heal with significant residual deformity. Historically, children with this type were often unable to walk and were wheelchair dependant. Significant short stature is a common feature of this type, as is dentinogenesis imperfecta. Type IV is a form that is intermediate in severity between types I and III with a variable fracture frequency, and the possibility of bone deformity. Stature is often normal in this type and characteristically the color of the sclera is white. In these four types abnormalities in synthesis of type 1 collagen can often be demonstrated with either a reduction in amount (Type I) or quality (Types II, III and IV). It is recognized that some children with osteogenesis imperfecta do not clearly fall into one of these four types. In recent years three additional forms of osteogenesis imperfecta have been identified based on a combination of phenotypic and bone histology features. Individuals with type V often exhibit exuberant hypertrophic callus formation following a fracture and have evidence of calcification of the interosseous membrane between the radius and ulna on X ray. Individuals with type VI have evidence of fish scale-like lamellation on bone histology. Type VII has only been reported in Quebec and is characterized by rhizomelia and coxa vara and, in contrast to the autosomal dominant inheritance seen in most types of osteogenesis imperfecta, is recessive. Type VII maps to chromosome 3 p 22–24 and is a hypomorphic defect of CRTAP gene.

Fig. (2-15): Showing Blue Sclera in Osteogenesis Imperfect. 66 Chapter 2: Disorders of Calcium and Bone Metabolism

Fig. (2-16): Showing Radiological Appearance in an Infant with Osteogenesis Imperfect. The diagnosis is confirmed by collagen biochemical studies or sequencing of DNA using fibroblasts cultured from a skin punch biopsy, or by direct sequencing of DNA from leukocytes. Identification of point mutations by sequencing facilitates family screening and prenatal detection. Severe OI can be detected prenatally by ultrasonography as early as 16 weeks of gestation. For recurrent cases, chorionic villus biopsy can be used for biochemical or molecular studies. The major causes of morbidity and mortality in OI are cardiopulmonary in origin. Recurrent pneumonia and declining pulmonary function occur in childhood, and corpulmonale is seen in adults. Neurologic complications include basilar invagination, brainstem compression, hydrocephalus, and syringohydromyelia. Most children with OI types III and IV have basilar invagination, but brainstem compression is infrequent.

Fig. (2-17): Showing Wheel Chair –Bound Child with Osteogenesis Imperfecta (Left) with multiple Bone Deformities (Right). Blueprint in Pediatric Endocrinology 67

Idiopathic Juvenile Osteoporosis It is a rare condition with an estimated incidence of 1 in 100,000 which characteristically presents in early puberty with back pain, difficulty walking and vertebral compression fractures. Its precise etiology is unclear although there is evidence of reduced bone formation on bone histology. Spontaneous resolution has been reported in this condition in some individuals while others go on to have a severe disabling condition with a potential loss of the ability to walk. A precise genetic cause for this condition has not yet been identified although there is a report of 3 of 20 individuals with idiopathic juvenile osteoporosis having heterozygous mutations in the gene for low-density lipoprotein receptor-related protein LRP5. Secondary Osteoporosis There are many chronic childhood conditions which have been labeled as causing osteoporosis. There are several etiological factors which act adversely, either alone or in a combination, on the bone development of a child with a chronic condition to increase their chances of developing osteoporotic fractures. Causes . Reduced mobility diseases; such as cerebral palsy, spinal cord injury, head injury, muscular dystrophy, spinal muscle atrophy and other neurodisability diseases. . Chronic inflammatory diseases are associated with osteoporotic fractures such as juvenile idiopathic arthritis, systemic lupus erythematosis and Crohn‘s disease. Increased circulating levels of cytokines such as IL-1, IL-6, IL-7, TNF α and TNFβ cause suppression of osteoblast recruitment and stimulate osteoclastogenesis producing an imbalance in bone turnover. . Steroid therapy has a variety of effects on calcium and bone metabolism including a direct effect on osteoblasts causing a reduction in bone formation, an inhibition of osteoprotegerin leading to increased bone resorption by stimulating osteoclastogenesis, a reduction in intestinal calcium absorption and an increased renal tubular calcium excretion. They often also cause a slowing of growth leading to delayed 68 Chapter 2: Disorders of Calcium and Bone Metabolism

puberty. They are used in many chronic childhood conditions because of their potent anti-inflammatory actions. . Endocrine disorders are associated with increased risk for osteoporosis in children which include: female hypogonadism secondary to Turner syndrome, hypothalamic amenorrhea, anorexia nervosa, premature and primary ovarian failure, Depot Medroxyprogestrone acetate and GnRH agonists therapies, estrogen receptor α mutations and hyperprolactinaemia while male hypogonadism is secondary to primary gonadal failure (Klinefelter‘s syndrome), idiopathic hypogonadotrophic hypogonadism and delayed puberty. Other endocrine causes include, hyperthyroidism, primary and tertiary hyperparathyroidism, Cushing‘s disease and growth hormone deficiency. . Malnutrition conditions in which osteoporosis are associated with poor nutrition and low body weight. This is well known for anorexia nervosa where the impact of low body weight on bone is augmented by the associated hypogonadism. Other disorders where nutrition is impaired include inflammatory bowel disease, malignancy and cystic fibrosis. Factors contributing to osteoporosis in these conditions including poor dietary calcium, protein intake and malabsorption. . Gastrointestinal disorders include malabsorption syndromes (cystic fibrosis, celiac disease), inflammatory bowel disease, chronic obstructive jaundice, primary biliary cirrhosis, alactasia and subtotal gastrectomy. . Bone marrow disorders include bone marrow transplant, lymphoma, leukemia, hemolytic anemia (sickle cell anemia, thalassemia) and systemic mastocytosis. . Medications include heparin, glucocorticosteroid, thyroxin, anticonvulsants, gonadotropin-releasing hormone agonists, and cyclosporine chemotherapy. Investigations Radiographs The examination of plain x ray can often be quite informative in a child with suspected osteoporosis. X -rays of long bones may show abnormalities in bone development such as the long slender lower limb bones seen in a non-weight-bearing child. Cortical thinning may be Blueprint in Pediatric Endocrinology 69

apparent with associated osteopenia and long bones may show deformity at the site of a previous fracture.

Fig. (2-18): Showing osteopenia and bone abnormalities. X - Ray of the lateral thoracic and lumbar spine may show characteristic wedge-shaped vertebral compression fractures or earlier changes with loss of vertebral height and shape. In addition there may be evidence of deformity such as a kyphosis or scoliosis and apparent osteopenia. Skull X ray in a child with suspected osteogenesis imperfecta may be informative if it shows the presence of excess numbers of Wormian bones (more than 10) and greater than 4×6 mm in size. However, it is recognized that their presence is not a consistent feature in children with osteogenesis imperfecta so their absence does not exclude this diagnosis. Laboratory . Most children with osteoporosis will not show abnormalities in standard indices of calcium and bone metabolism such as plasma calcium, phosphate, alkaline phosphatase, 25 hydroxyvitamin D and serum parathyroid hormone. However, these should be checked to exclude the possibility of osteomalacia which can present with osteopenia bones and fractures. It is also important to ensure that any vitamin D deficiency is corrected before the potential use of a bisphosphonate drugs in treatment . There are many biochemical markers of bone turnover available which can be measured in blood or urine and reflect bone formation and bone resorption. The range of bone turnover markers seen in growing children is wide, with significant increases during the infancy and puberty growth spurts. Therefore they are not useful as a diagnostic 70 Chapter 2: Disorders of Calcium and Bone Metabolism

investigation in a child with suspected osteoporosis but can be of benefit in monitoring response to treatment. . In a child with suspected secondary osteoporosis the following may also be informative: full blood count, erythrocyte sedimentation rate, C-reactive protein, celiac antibody screen, insulin-like growth factor 1 and thyroid function tests. Genetics . In a child who has no clear explanation for osteoporosis there may be value in looking for genetic abnormalities for primary osteoporosis. Mutation of COL1A1 and COL1A2, are the two genes coding for type 1 collagen in approximately 90% of individuals with osteogenesis imperfecta. Alternatively, a skin biopsy can be obtained to produce a fibroblast culture which can then be examined for quantitative or qualitative abnormalities in type 1 collagen synthesis. However, up to 15–20% of individuals with osteogenesis imperfecta will have negative results. Recently, two genes for recessive forms of osteogenesis imperfecta have been identified. However, these types are rare and the clinical phenotype quite distinctive and as such they are unlikely to present as one of the milder forms of osteogenesis imperfecta. . Currently, the cost of genetic testing of DNA sample is quite expensive and therefore would only be justified if a diagnosis of osteogenesis imperfecta cannot be made on the basis of the clinical history and examination. . It is important to screen for the mutations in LRP5 gene in idiopathic osteoporosis. Bone Biopsy The direct examination of bone by obtaining a bone biopsy may on selected occasions add useful information to the etiology of osteoporosis. This is usually obtained from the iliac crest under short general anesthesia. However, in clinical practice there are limited indications for bone biopsy if the etiology is otherwise apparent. It is a potentially useful investigation in a child with osteoporosis with no obvious cause because idiopathic juvenile osteoporosis is characterized by low bone turnover and a marked reduction in cancellous bone volume. However, it is Blueprint in Pediatric Endocrinology 71

important that any specimens are examined by a histopathologist who is familiar with bone biopsies in children. Bone Mineral Densometry (BMD) The assessment of bone density can be an important and an informative investigation in a child with suspected osteoporosis. The most frequently used modality is DXA due to its availability, speed of scan acquisition and low radiation dose. There are however some potential pitfalls in its use in children that are not always readily appreciated by clinicians requesting scans and those reporting the scan results. One potential error is the use of a T score as in adult practice, in which the child‘s bone density is compared to that of a young adult which would be similar to comparing the height of a child to an adult. Nowadays, most manufacturers do not provide the option of calculating a T score with the pediatric software rather using Z score in children. Another potential problem is the use of inappropriate reference data which have been collected on a different model of scanner than the one being used. Therefore, it is important to have reference data collected on the same type of scanner and on children of the same gender and ethnic group. A fundamental problem with the use of DXA in children is that the bone density value produced in gm/cm2 is an areal bone density (aBMD) that is, the bone mineral content of the bone being scanned is divided by its bone area. This fails to take account of the third dimension and does not provide a volumetric bone density (vBMD) where bone mineral content is divided by bone volume to produce results in gm/cm3. There is a strong correlation between areal bone density and bone size and thus height. This means in practice a child who is short for their age will have smaller bones and therefore their areal bone density will be below the mean value for a child of the same age, entirely because of their short stature. The worst case scenario is that a small child is inappropriately diagnosed as having ―osteoporosis‖ with a resultant change in their lifestyle and potentially inappropriate treatment to improve their low bone density. Up to 50% of children had received an inappropriate diagnosis of osteoporosis as a result of errors in interpretation of their DXA scan results. . There are several different techniques that have been proposed to adjust for body size when interpreting bone density scan results in 72 Chapter 2: Disorders of Calcium and Bone Metabolism

children. One approach is to calculate a volumetric bone density (vBMD) by estimating bone volume from the projected bone area-often referred to as bone mineral apparent density (aBMD) for which published reference data are now available.

A child with short stature would be identified as having short bones whereas a child with narrow and /or thin bones would potentially have bone fragility. A third technique uses a functional approach whereby bone strength is related to muscle strength by assessing bone mineral content in relation to lean body mass as a surrogate marker for muscle strength. As yet it is not apparent that any one of these approaches is superior to the others as a predictor of fractures. However, it is important that some methods for body size adjustment are used, particularly when assessing bone density in children who are short for their age as may often be the case with chronic disease. Prevention and Therapy of Osteoporosis In children and adolescents, calcium intakes of 1000 to 1200 mg/day are recommended. Most studies indicate that calcium supplementation slows bone loss; moreover, low calcium intakes in the presence of low calcium absorption increase the risk of hip fracture. High calcium intakes are generally safe, although it may be worthwhile to check urinary calcium levels. Vitamin D intake should be at least 400 U/day, and up to 2000 U/day has been suggested; higher levels may produce hypercalciuria or hypercalcemia. Calcium and vitamin D increase bone mass, decrease seasonal bone loss and can decrease the incidence of fractures, particularly in populations likely to have deficient intakes or limited sun exposure. Dietary intakes of other minerals and of vitamins C which are important for bone matrix synthesis, as well as protein, should be adequate. With regards to children who have sustained osteoporotic fractures, treatment with bisphosphonate showed great benefits. Although there are now many different bisphosphonate available that vary in potency and methods of administration most of the studies undertaken in children have used the intravenous preparation like pamidronate or Zoledronic acid. There are now many studies in children with different conditions which have shown an improvement in bone density with the use of Blueprint in Pediatric Endocrinology 73

bisphosphonate but relatively few that have shown a reduction in fracture incidence. Intravenous bisphosphonate are also effective at relieving pain associated with vertebral compression fractures. There are a number of potential side effects of bisphosphonate including the acute phase reaction seen on first exposure and gastrointestinal upset seen with some oral bisphosphonate. They can cause symptomatic hypocalcaemia if used where there is pre-existing vitamin D deficiency or hypoparathyroidism. They have been shown to delay bone healing after elective osteotomies in children with osteogenesis imperfecta. There is no evidence that they compromise longitudinal bone growth, although they have a long half-life in the skeleton with evidence of urinary excretion up to eight years after cessation. In view of this there are concerns about potential teratogenicity if taken by women of child-bearing age although as yet there is no evidence of this. There have been numerous reports of the development of osteonecrosis of the jaw in individuals on bisphosphonate. This is a condition where necrotic painful lesions in the jaw show delayed healing. These reports, which to date have only been in adults, are in individuals who usually have malignancies or poor dental hygiene and have received high doses of potent intravenous bisphosphonate such as pamidronate or zoledronate, although there are some reports of this with oral bisphosphonate. Bisphosphonate-induced osteopetrosis has also been reported in a child who was treated inappropriately. Such reports demonstrate the potential for serious adverse effects, and clinicians contemplating their use in a child should discuss these potential risks and provide appropriate written information. . Acute reactions seen on first exposure to intravenous bisphosphonate therapy include: . Acute drop in serum calcium, fever, flue-like illnesses, bone pain and poor intake. . These symptoms usually doesn‘t last more than 2-3 days post first infusion. . Repeated doses usually associated with none of these manifestations. 74 Chapter 2: Disorders of Calcium and Bone Metabolism

. Long term side effects not known in children yet reported, although my personal observations of no long term side effects seen one for the last 12 years of using Bisphosphonates. References 1. Fewtrell, M.S., on behalf of the British Paediatric and Adolescent Bone Group. (2003) Bone densitometry in children assessed by dual x ray absorptiometry: uses and pitfalls. Archives of Disease in Childhood 88: 795–798. 2. Kruse, K. (1992) Vitamin D and parathyroid. In: Functional Endocrinologic Diagnostics in Children and Adolescents (ed. M.B. 3. Ranke, 1st edn, pp. 153–167. J & J Verlag, Mannheim. Kruse, K., Kracht, U. & Gِpfert, G. (1982) Renal threshold phosphate .4 concentration (TmPO4/GFR).Archives of Disease in Childhood 57, 217–223. 5. Marini, J.C. (2003) Do bisphosphanates make children‘s bones brittle or better? New England Journal of Medicine 349: 423–426. 6. Reid, I.R. (ed.) (1997) Baillière‘s Clinical Endocrinology and Metabolism: Metabolic Bone Disease. Ballière Tindall, London. 7. Shaw, N.J., Wheeldon, J. & Brocklebank, J.T. (1990) Indices of intact serum parathyroid hormone and renal excretion of calcium, phosphate and magnesium. Archives of Disease in Childhood 65: 1208–1211. 8. Singh, J., Moghal, N., Pearce, S.H.S. & Cheetham, T. (2003) The investigation of hypocalcaemia and rickets. Archives of Disease in Childhood 88: 403–407. 9. Wharton, B. & Bishop, N. (2003) Rickets. Lancet 362, 1389–1400.

Chapter 3

Disorders of Sex Development

. Introduction . Classification of disorders of sexual development . Stages of sexual differentiation . Sex differentiation in embryo and fetus . Gonadal differentiation . Causes of abnormal sexual differentiation . Virilized females or 46XX DSD . Feminized males or 46 XY DSD . Isolated deficiency of Müllerian duct Inhibiting Hormone . Chromosomal defects may cause a variety of possible effects . Congenital Adrenal hyperplasia . Adrenal steroid biosynthetic pathway . Adrenal steroid enzymes . Forms of 21-hydroxylase deficiency . Lipoid adrenal hyperplasia . Steroidogenic factor-1 (SF-1) deficiency . Maternal androgens . Aromatase enzyme deficiency . XX Male Syndrome . Persistent Müllerian Duct Syndrome (PMDS) . Gonadotrophin deficiency causing DSD . Leydig cell agenesis . Testosterone biosynthesis defects . Androgen Insensitivity Syndrome (AIS) . 5-alpha-reductase type 2 deficiency . Ovotesticular disorders of sexual development . Partial gonadal dysgenesis . Pure gonadal dysgenesis . XY Female Syndrome . Diagnosis of CAH . Medical management of CAH

77 76 Chapter3: Disorders of sex development

. Considerations for sex assignment in CAH . Corrective surgery . Prenatal treatment of CAH . Dysmorphic syndromes with DSD . Clitoromegaly . Micropenis o Causes o Investigations o Treatment . Hypospadias . Cryptorchidism o Causes o Investigations o Treatment . Retractile testicle(s)

Introduction Disorders of sexual development (DSD) are congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Disorders of sex development (DSD), formerly termed intersex are among the most fascinating conditions encountered by the clinician. Usually children present at birth with ambiguous genitalia (genital phenotype that is neither clearly male nor female). Most causes are genetic. One exception is virilisation of a 46, XX fetus due to maternal virilizing tumors or maternal exposure to androgenic drugs. . Chromosomal sex determines gonadal sex, which determines phenotypic sex. The type of gonad present determines the differentiation/regression of the internal ducts (müllerian and Wolffian ducts) and ultimately determines the phenotypic sex. Gender identity is determined not only by the phenotypical appearance of the individual but also by the brain's prenatal and postnatal development as influenced by the environment. . The incidence of DSD at birth is estimated at 1 in 4500 live births.

. The incidence of 46, XY DSD is estimated at 1 in 20,000 live male births.

. In infants with unilateral or bilateral non-palpable gonads and hypospadias, almost 50% have a DSD.

Fig. (3-1): Showing Infant Wit DSD

77 78 Chapter3: Disorders of sex development

Table (3-1): Classification of Disorders of Sexual Development.

Revised Previous 46,XX DSD Female pseudohermaphrodite 46,XY DSD Male pseudohermaphrodite Ovotesticular DSD True hermaphrodite 46,XX testicular DSD XX male 46,XY complete gonadal dysgenesis XY sex reversal

Stages of Sexual Differentiation Normally sex differentiation proceeds in an orderly way with each level determining the next stage. . Chromosomal sex (46 XY or 46 XX). . Gonadal sex (testis or ovary). . Internal duct sex (male or female internal genital organs). . External duct sex (male or female external genitalia). Sex Differentiation in Embryo and Fetus Both female and male fetuses have an indifferent gonad, Müllerian and Wolffian ducts internally and a urogenital sinus leading to the exterior. In females the indifferent gonad becomes an ovary. If the gonad is an ovary (or if the gonad is absent) then, the Wolffian duct atrophies, the Müllerian duct develops into the fallopian tubes, uterus and cervix and the urogenital sinus develops into the female phenotype with a vagina, labia and clitoris. In males the SRY region on the Y chromosome contains a testis determining factor which directs an indifferent gonad to develop into a testis. If the gonad is a testis, then it secretes Müllerian Inhibiting Hormone (MIH), causing regression of the Müllerian duct. Testosterone will be causing development of the Wolffian duct into the epididymis, vas deferens and seminal vesicles. In the urogenital sinus, testosterone secreted from the testis is converted to dihydrotestosterone causing masculinization of the urogenital sinus into penis, scrotum. Both female Blueprint in Pediatric Endocrinology 79

and male fetuses have an indifferent gonad, Müllerian and Wolffian ducts internally and a urogenital sinus leading to the exterior. Gonadal Differentiation During the second month of fetal life, the indifferent gonad is guided to develop into a testis by testis-determining factor (TDF) on the short arm of the Y chromosome; an area termed the sex-determining region of the Y chromosome (SRY). When this region is absent or altered, the indifferent gonad develops into an ovary. The existence of patients with 46, XX testicular DSD, who have testicular tissue in the absence of an obvious Y chromosome or SRY genetic material, clearly requires other genetic explanations. Other genes important to testicular development include DAX1 on the X chromosome, SF1, WT1, SOX9, and AMH. Fetal ovaries develop when the TDF gene (or genes) is absent. When testicular tissue is absent, the fetus morphologically begins and completes the internal sex duct development and external phenotypic development of a female. When testicular tissue is present, two produced substances appear to be critical for development of male internal sex ducts and an external male phenotype, namely, testosterone and müllerian-inhibiting substance (MIS) or AMH. Testosterone is produced by testicular Leydig cells and induces the primordial Wolffian (mesonephric) duct to develop into the epididymis, vas deferens, and seminal vesicle. No Wolffian development is expected in association with a streak gonad or a non–testosterone-producing dysgenetic testis. MIS is produced by the Sertoli cells of the testis and is critical to normal male internal duct development. MIS is secreted by the testis beginning in the eighth fetal week. The prime role of MIS is to repress passive development of the müllerian duct (fallopian tubes, uterus, and upper 2 / 3 of the vagina). . MIS represses müllerian duct development, while testosterone stimulates Wolffian duct development The external genitalia of both sexes are identical during the first 7 weeks of gestation. Without the hormonal action of the androgens testosterone and dihydrotestosterone (DHT), external genitalia appear phenotypically female. In the gonadal male, differentiation toward the male phenotype actively occurs over the next 8 weeks. This 80 Chapter3: Disorders of sex development

differentiation is moderated by testosterone, which is converted to 5- DHT by the action of an enzyme, 5-alpha reductase, in turn, these actions lead to normal male external genital development from primordial parts, forming the scrotum from the genital swellings, forming the shaft of the penis from the folds, and forming the glans penis from the tubercle. The prostate develops from the urogenital sinus.

Incomplete masculinization occurs when testosterone fails to convert to DHT or when DHT fails to act within the cytoplasm or nucleus of the cells of the external genitalia and urogenital sinus. The timing of this testosterone-related developmental change begins at approximately 6 weeks of gestation with a testosterone rise in response to a surge of luteinizing hormone. Testosterone levels remain elevated until the 14th week. Most phenotypic differentiation occurs during this period. After the 14th week, fetal testosterone levels settle at a lower level and are maintained more by maternal stimulation through human chorionic gonadotropin (HCG) than by LH. Testosterone's continued action during the latter phases of gestation is responsible for continued growth of the phallus, which is directly responsive to testosterone and to DHT.

. Hypospadias occurs at a rate of 1 case per 300 live male births . In less than 1% of patients, hypospadias occurs in combination with undescended testes. . Clinicians should suspect the possibility of a DSD in patients with both hypospadias and cryptorchidism. . The most common disorder of sexual development (DSD), congenital adrenal hyperplasia (CAH), results in virilization of a 46, XX female and thus is classified under the heading of 46, XX DSD. . A family history of genital ambiguity, infertility, or unexpected changes at puberty may suggest a genetically transmitted trait. . Recessive traits tend to occur in siblings, while X-linked abnormalities tend to appear in males who are scattered sporadically across the family history. . A history of early death of infants in a family may suggest a previously missed adrenogenital deficiency. Blueprint in Pediatric Endocrinology 81

. Maternal drug ingestion is important, particularly during the first trimester, when virilization may be produced exogenously in a gonadal female and a history of maternal virilization may suggest an androgen- producing maternal tumor (arrhenoblastoma). Key points

. External genitalia examination should include the size and degree of differentiation of the phallus, the position of the urethral meatus, labioscrotal folds which may be separated or folds may be fused at the midline, giving an appearance of a scrotum and presence of increased pigmentation. . Documentation of palpable gonads is important. Although ovotestes have been reported to descend completely into the bottom of labioscrotal folds, in most patients, only testicular material descends fully. . Impalpable gonads, even in an apparently fully virilized infant, should raise the possibility of a severely virilized 46, XX DSD patient with CAH. . Rectal examination may reveal the cervix and uterus, which is relatively enlarged in a newborn because of the effects of maternal estrogen, permitting easy identification.

Fig. (3-2): Showing a 46, XY DSD (Masculinized appearance of the genitalia wth an enlarged phallus and scrotal appearance of the Labia) . Infants born with DSD represent a true medical and social emergency. . DSD can be classified as sex chromosomal, 46, XX, or 46, XY. 82 Chapter3: Disorders of sex development

. CAH is the most common cause of 46, XX DSD. If unrecognized, the resulting hypotension can cause vascular collapse and death. . Male infants with this syndrome may be phenotypically normal, and the diagnosis may be missed. . Mixed gonadal dysgenesis is the second most common cause of all DSD. It has a variable presentation. . 46, XY DSD can be due to several etiologies and requires a more extensive diagnostic evaluation. . Diagnosis in a child with ambiguous genitalia is a clinical emergency that should be managed in an institution with expertise in endocrinology, genetics, and surgery, and with appropriate psychosocial support. . Management usually includes a combination of surgery and hormonal treatment. . Long-term medical outcome is very good, although there may be physical and psychological consequences. Parental Counseling . Both parents should be available, and discussion should be in a quiet room with tissues and water available. . Parents should see the genitalia themselves. . Clear statement that it will be possible to decide whether the child is either male or female and never a "Third Sex". . Investigations are needed to determine the sex identity . Postpone naming of the baby & birth certificate till tests results are ready. . When results back, the diagnosis, prognosis and treatment options are fully discussed . Parents should be involved in taking the decision of ―gender assignment‖ and how the child will develop sexually as an adult. . Preferable to provide parents of some written information and reliable websites for them to read more on this subject. Blueprint in Pediatric Endocrinology 83

Causes of Abnormal Sexual Differentiation There are a number of causes which interfere with normal sex differentiation resulting in sexual ambiguity. Virilized Females or 46XX DSD . Androgens may be formed by fetal adrenals if fetus has CAH. . Placental aromatase enzyme deficiency. . Accidental androgen ingestion by mother (e.g, danazol) . Maternal androgen secreting ovarian tumor. Feminized Males or 46 XY DSD . Hypoplastic testes due to fetal LH deficiency. . LH receptor mutation. . Dysplastic testes. . Testosterone biosynthesis defects. . Failure of testosterone conversion to dihydrotestosterone due to 5 –α- reductase enzyme deficiency. . Androgen receptor defects; whether is complete or partial defect . Complete androgen insensitivity syndromes, previously "Testicular Feminization". . Partial androgen insensitivity syndrome. Isolated deficiency of Müllerian duct Inhibiting Hormone . 46 XY males with uterus. Chromosomal Defects may Cause a Variety of Possible Effects . Absence of part of Y may yield 46 XY infant with female phenotype and streak ovaries. . Transfer of part of Y into an X may yield a 46 XX infant with male phenotype and testes. Congenital Adrenal Hyperplasia (CAH) Overall, CAH is the most frequent cause of DSD in the newborn, constituting approximately 60% of all DSD cases. CAH presents a 84 Chapter3: Disorders of sex development

spectrum of abnormalities, including the degree of phallic enlargement, the extent of urethral fold fusion, and the size and level of entry of the vagina into the urogenital sinus. Internal müllerian structures are consistently present. In 90 – 95 % of patients with CAH, the block is at the 21-hydroxylation enzyme. This leads to a glucocorticoid and mineralocorticoid deficiencies and a buildup of androgenic byproducts, which causes masculinization of a female fetus. The result is a female infant with varying degrees of virilization. 75% of patients have salt- wasting. The 21-β-hydroxylase defect is inherited as an autosomal recessive trait closely linked to the human leukocyte antigen (HLA) locus on chromosome 6. Diagnosis is confirmed by an elevated serum level of 17-hydroxyprogestrone.Patients who have CAH due to 11-β-hydroxylase block accumulate deoxycorticosterone (DOC) and 11-deoxycortisol which exhibits salt retention and hypertension because DOC is a potent mineralocorticoid. 3-β-hydroxysteroid dehydrogenase deficiency is less frequent seen which causes less severe virilization of a female infant than the virilization caused by 21-β-hydroxylase or 11-β-hydroxylase deficiency. The buildup of pregneninolone, which is subject to hepatic conversion into testosterone, produces the virilization.

Fig. (3-3): Neonate with DSD due to Congenital Adrenal Hyperplasia. Blueprint in Pediatric Endocrinology 85

Fig. (3-4): Showing Adrenal Steroidogenesis Pathway Adrenal Steroid Enzymes Series of enzymes are involved in the process of steroidogenesis including; StAR carrier protein, P-450 Cholesterol side chain cleavage enzyme, 17-Hydroxylase enzyme, 3β-HSD enzyme, 21-Hydroxylase enzyme, 11-Hydroxylase enzyme and aldosterone synthase enzyme. As consequence of cortisol deficiency, the fetal pituitary secretes excess ACTH, which leads to hyperplasia of the congenital adrenal gland and stimulation of adrenal steroid biosynthesis. Depending on the affected enzyme, under-or over production of adrenal androgens, the clinical features of CAH vary depending upon the degree of cortisol and mineralocorticoid deficiency or androgen excess. Forms of 21-Hydroxylase Deficiency (21 OH) The clinical spectrum of 21-OH deficiency ranges from mild to severe forms reflecting varying degrees of the enzyme‘s deficiency. . Classical CAH is the most severe form and presents at birth or soon after. It may be salt-losing or non salt-losing clinically depending on the degree of co-existing mineralocorticoid deficiency. . Non-classical CAH due to mild enzyme deficiency which presents later on in the childhood or even adulthood with androgen 86 Chapter3: Disorders of sex development

excess (precocious puberty, severe acne, hirsutism, and amenorrhea) but not with clinical signs of glucocorticoid or mineralocorticoid deficiency. Lipoid Adrenal Hyperplasia . The cause of lipoid adrenal hyperplasia is a mutation in the gene for the steroid acute regulatory protein (StAR). The StAR protein transports cholesterol across the mitochondrial membrane and in its absence, steroid biosynthesis from cholesterol cannot take place and lipoid droplets accumulate in the cytoplasm of steroidogenic cells of the adrenal cortex and gonads, making these organs enlarged and dysfunctional. The hyperplastic adrenals have a bright yellow colour. An infant born with the complete form of the condition will be phenotypically female regardless of genotype, will have ACTH-related hyperpigmentation of the skin and will develop severe adrenal insufficiency with hyponatraemia, hyperkalemia and hypoglycemia in the first postnatal week. Milder forms of the condition occur and patients with these can present months or years after birth with adrenal insufficiency. Treatment with hydrocortisone and fludrocortisone leads to a good outcome. Sex hormone replacement with estrogen at puberty is necessary for the development of secondary sex characteristics. Genetic female patients will have a uterus and will therefore need a progestogen in addition to estrogen. Steroidogenic Factor-1 (SF-1) Deficiency . SF-1 is expressed in the developing adrenals, gonads and hypothalamus. A child with a complete defect in SF-1 would show failure of adrenal and gonadal development and would be born female regardless of genotype. Gonadotrophin levels would, however, be low because of a deficiency of hypothalamic GnRH. Heterozygous SF1 mutations are much more common than was previously thought and can present as a child with penoscrotal hypospadias, micropenis and bilateral anorchia, micropenis and undescended testes, or as premature ovarian failure in an otherwise healthy girl In all of these examples, adrenal function has generally been normal but whether or not in the longer term adrenal insufficiency will ensue is unknown. Similarly, it is unknown if DSD or hypospadiac patients with SF-1 mutations will have normal puberty and fertility or if there is an increased risk of testicular tumors Blueprint in Pediatric Endocrinology 87

due to gonadal dysgenesis. Long term surveillance of gonadal and adrenal status is advised. Key Points . Autosomal recessive transmission with equal sex affection. . Carrier rate is 1/50 with incidence 1/10,000 (severe forms), 1/100 - 1/1000 (milder forms, depending upon population). . Gene for the 21-hydroxylase enzyme, CYP 21B, is on the 6th chromosome near the HLA genes. . Prenatal diagnosis is possible (gene mutation, karotyping, HLA, amniotic steroids). . Prenatal therapy prior to sixth week of gestation is effective in preventing genital virilisation of affected female, but not to prevent the diseases.

Maternal Androgens . Virilization of a female fetus may occur if progestational agents or androgens are used during the first trimester of pregnancy. After the first trimester, these drugs cause only phallic enlargement without labioscrotal fusion. The incriminated drugs were formerly administered to avoid spontaneous miscarriages in patients who had a history of habitual abortion. Various ovarian tumors (arrhenoblastoma, luteomas, lipoid tumors of the ovary, stroma cell tumors) reportedly have produced virilization of a female fetus. Aromatase Enzyme Deficiency In genotypic females, aromatase deficiency during fetal life leads to 46, XX DSD and results in hypergonadotropic hypogonadism at puberty because of ovarian failure to synthesize estrogen. Mutations in CYP19 cause aromatase deficiency in both the fetus and the placenta. The placenta can convert DHEA sulfate to androstenedione and testosterone normally, but it cannot convert these androgens to estrone and estradiol, respectively. These androgens accumulate in both the fetal and maternal circulations and virilize both the mother and the affected fetus if it is female. Affected male infants are phenotypically normal. Affected female patients virilize further at puberty if they are untreated. 88 Chapter3: Disorders of sex development

. The lack of aromatase activity within bone leads to tall stature in both sexes, because estrogens are required to close the growth plates, and later to osteoporosis.

XX Male Syndrome Males with a 46XX karyotype have normal external and internal male genitalia; however, they resemble patients with Klinefelter's syndrome in that they have small testes, azoospermia, and infertility. Translocation of the SRY gene to the X chromosome is detected in 75 to 90% of sporadic cases; this can occur because the gene is located very near the pseudoautosomal region in which the short arms of the X and Y chromosomes are homologous and meiotic recombination is possible. Duplication of the SOX9 transcription factor may be responsible for some familial cases of XX sex reversal.46XY disorders of sexual development (formerly termed male pseudohermaphroditism) Persistent Müllerian Duct Syndrome (PMDS) Persistent müllerian duct is a rare autosomal recessive condition that results from mutations in the genes for either AMH (type I) or its receptor (type II). It is a rare syndrome and usually does not present in the newborn period because the genitalia appear to be those of a male with undescended testes. The most common presentation is a phenotypic male with an inguinal hernia on one side and an impalpable contralateral gonad. Herniorrhaphy reveals a uterus and fallopian tube in the hernia sac. Appropriate surgical management attempts to bring the testes into the scrotum based on the rationale that testis tumors may occur later, emphasizing the need to remove any testicular tissue that cannot be palpated. Incidence of malignancy is unknown compared to the usual cryptorchid testis. Removal of müllerian remnants is unnecessary, since the remnants rarely produce symptoms and have no reported history of subsequent malignancy. Gonadotrophin Deficiency Causing DSD Milder or later-appearing deficiencies of androgen biosynthesis (after 13 to 14 weeks) may allow complete fusion of the labioscrotal folds and normal positioning of the urethral meatus, but subsequent growth of the phallus is suboptimal. Such individuals have a micropenis. The most common cause is lack of gonadotropin (specifically, LH) Blueprint in Pediatric Endocrinology 89

secretion; even when LH is lacking, early male developm ent is normal because testosterone secretion is controlled mostly by hCG during the first trimester. Defective LH and follicle-stimulating hormone (FSH) secretion can result from failure of migration into the hypothalamus of the neurons that normally secrete gonadotropin-releasing hormone. This condition, Kallman's syndrome, is most often X-linked, resulting from mutations in the KAL1 gene. It is often associated with anosmia. Leydig Cell Agenesis Leydig cell agenesis or hypoplasia is a rare autosomal recessive syndrome caused by mutations in the LHGCR gene encoding the LH receptor. Without stimulation by LH (or by hCG early in gestation), Leydig cells do not differentiate normally and do not secrete testosterone, affected male infants are born with female-appearing or ambiguous external genitalia. Müllerian structures are absent because of unaffected secretion of AMH by Sertoli cells. LH levels are high in infancy and at puberty, and they respond normally to gonadotropin-releasing hormone, whereas testosterone levels are low and do not respond to stimulation by hCG. Affected female patients are phenotypically normal but may have oligomenorrhoea resulting from primary ovarian dysfunction. Testosterone Biosynthesis Defects Production of testosterone from cholesterol involves 5 enzymatic steps, of these enzymes, 20-alpha hydroxylase, 3-beta-hydroxysteroid dehydrogenase and 17-alpha hydroxylase are shared with the adrenal glands, and their deficiency leads to ambiguous genitalia and symptoms of CAH. Both 17, 20 desmolase and 17-ketosteroid reductase occur only as part of normal androgen synthesis, so their defects, while associated with genital abnormalities, are not associated with CAH. During the neonatal period, these patients present as 46, XY gonadal males with poor virilization and ambiguous genitalia. The genitalia respond to exogenously administered testosterone. Children with CAH manifestations also require treatment with steroid and mineralocorticoid replacement. Genetic counseling is desirable because 17-alpha hydroxylase and 3-beta-hydroxysteroid dehydrogenase deficiencies are transmitted as autosomal recessive traits. Additional rare causes for deficiencies in testosterone production include Leydig cell agenesis, 90 Chapter3: Disorders of sex development

Leydig cell hypoplasia, abnormal Leydig cell gonadotropin receptors, and delayed receptor maturation. Androgen Insensitivity Syndrome (AIS) This is one of the most frequent forms of male SDS, and it occurs in approximately 1 in 20,000 male births. Males normally carry a single copy of the X-linked androgen receptor gene. Single mutation can completely inactivate the receptor in males and can lead to complete androgen insensitivity (formerly termed testicular feminization syndrome). . Patients with the complete form of androgen insensitivity have normal female external genitalia. The condition is rarely discovered before puberty unless the testes are palpated in the groin or labia on routine examination. Because the testes secrete AMH, müllerian structures are absent, including the uterus, fallopian tubes, and cervix. The vagina is usually shallow and ends blindly. Wolffian structures are also absent because their development depends on androgens. The testes may be located in the abdomen or in the labia majora and do not undergo spermatogenesis. AMH levels are elevated during the first year and (if the testes have not been removed) after puberty. Testosterone and LH levels in infancy and at puberty are elevated as a result of defective feedback regulation caused by androgen resistance at the level of the hypothalamus. At puberty, pubic and axillary hair is scant or absent "labeled as a clean angel". Testosterone can be aromatized to estradiol by CYP19 in breast fat, and estrogen receptors are unaffected in this condition. Thus, breast development is that of a normal female. Incomplete androgen insensitivity (Reifenstein's syndrome) is characterized by a variable degree of genital ambiguity, and both virilization and breast development occur at puberty. Mild androgen insensitivity can also occur with a male phenotype, with gynaecomastia and infertility as the sole manifestations. Mutations in the androgen receptor are not detected in many mild cases, which may result from defects in other factors affecting actions of the receptor. 5-α-Reductase Type 2 Enzyme Deficiency Is an autosomal recessive sex-limited condition resulting in the inability to convert testosterone to the more physiologically active dihydrotestosterone (DHT) with an overall incidence of 1 in 5500 live Blueprint in Pediatric Endocrinology 91

births. Because DHT is required for the normal masculinization of the external genitalia in utero, neonates usually presents with striking ambiguity of the genitalia, with a clitoral-like phallus, severely bifid scrotum, perineoscrotal hypospadias, and a rudimentary prostate. Occasionally, patients can appear more masculinized; they may lack a separate vaginal opening, have a blind vaginal pouch that opens into the urethra, and have isolated penile hypospadias or even a penile urethra. The uterus and fallopian tubes are absent because of the normal secretion of the müllerian-inhibiting factor. Testes are intact and are usually found in the inguinal canal or scrotum; however, cryptorchidism is frequently described with testes occasionally located in the abdomen. Wolffian duct differentiation is normal with seminal vesicles, vasa differentia, epididymides, and ejaculatory ducts. The prostate is small, non palpable, and rudimentary in adulthood. Diagnosis is confirmed by the presence of a high ratio of serum testosterone to DHT.HCG stimulation test, which may be useful to exaggerate the testosterone-to-DHT ratio characteristic of this syndrome. The reference range testosterone-to-DHT ratio is 8- 16:1, while patients with 5-alpha-reductase deficiency characteristically have a ratio greater than 30:1. Cultured skin fibroblasts demonstrate decreased 5-alpha-reductase activity. Ovotesticular Disorders of Sexual Development (formerly true hermaphroditism) Both ovarian and testicular tissues are present in ovotesticular DSD, an uncommon cause of genital ambiguity for fewer than 10% of DSD cases. Appearance of the genitalia varies widely in this condition. While ambiguity is the rule, the tendency is toward masculinization. The most common karyotype is 46, XX, although mosaicism is common. A translocation of the gene coding for HY antigen from a Y chromosome to either an X chromosome or an autosome presumably explains the testicular material in a patient with a 46, XX karyotype. More problematic is how a patient with a 46, XY karyotype can have ovarian tissue, since two X chromosomes are believed to be necessary to normal ovarian development. Possibly, unidentified XX cell lines are present in these patients. Gonads may contain combination of ovary, testis, or ovotestis which is the most common and is found in approximately two thirds of patients. 92 Chapter3: Disorders of sex development

When an ovotestis is present, one third of the patients exhibit bilateral ovotestis. A testicle, when present, is more likely to exist on the right, and an ovary, when present, is more common on the left. A palpable gonad is present in patients with an ovotestis. An ovary, when found, is situated most commonly in the normal anatomic intra-abdominal position, while testis is found approximately two thirds of the time in the scrotum, emphasizing that normal testicular tissue is most likely to descend fully. Ovotestes may present with either a fallopian tube or a vas deferens but usually not both. If a fallopian tube has a fimbriated end, the end is closed in most patients, perhaps contributing to the usual lack of fertility. Partial Gonadal Dysgenesis Partial gonadal dysgenesis can be as either 46, XY or mosaicism (45, X/46, XY). These represent a spectrum of disorders in which the gonads are abnormally developed.Typically, at least one gonad is either dysgenetic or a streak. Dysgenetic testis histologically demonstrates immature and hypoplastic testicular tubules in a stroma characteristic of ovarian tissue but that lack oocytes. Spectrum of faulty testicular differentiation, with streak gonad at one end of the spectrum, and dysgenetic testis lying between streak gonad and a normal testis. Pure Gonadal Dysgenesis This class of DSD, with bilateral streak gonads appearing as ovarian stroma without oocytes, usually goes unrecognized in newborns because the phenotype is typically completely female. Patients tend to present at puberty, at which point they do not undergo normal pubertal changes. Girls with Turner syndrome (45, XO) may be detected earlier by noting the characteristic associated anomalies of short stature, webbing of the neck, and wide-spaced nipples. Neither Turner syndrome nor the 46, XX type of pure gonadal dysgenesis appear to be associated with increased risk of gonadal malignancy. Therapy in these children is primarily limited to appropriate estrogen and progesterone. The 46, XY type of pure gonadal dysgenesis poses a different problem because the bilateral streak gonads carry a significant potential for malignancy. Nearly one third of patients develop a dysgerminoma or gonadoblastoma; therefore, gonadectomy becomes important as soon as Blueprint in Pediatric Endocrinology 93

the diagnosis is recognized. Pure gonadal dysgenesis syndromes represent opportunities for genetic counseling. Turner syndrome appears sporadically, however, the 46, XX type of pure gonadal dysgenesis appears to have an autosomal recessive transmission, and the 46, XY type is apparently an X-linked recessive trait. XY Female Syndrome Patients with pure XY gonadal dysgenesis (Swyer's syndrome) have a normal female phenotype, including uterus and fallopian tubes, but they have streak gonads. These patients are free of Turner-like malformations and attain normal height. Mutations of the SRY gene have been identified in 15% of cases. Unlike 45, X patients with Turner's syndrome, these patients have an increased risk of gonadoblastoma. Similar phenotypes result from duplication of the region of the X chromosome containing the DAX1 gene, from duplication of the WNT4 gene, or from haploinsufficiency of the SF1 transcription factor (associated in some cases with adrenal hypoplasia). XY sex reversal can also result from mutations in the SOX9 transcription factor, associated with a form of dwarfism, camptomelic dysplasia. Mutations of DHH cause XY gonadal dysgenesis, associated with peripheral neuropathy. Other 46, XY patients with absent gonads have various degrees of sexual ambiguity and no müllerian derivatives. The implication that some testicular tissue was functional at least up to 10 weeks and subsequently regressed led to the name fetal testicular regression syndrome. Testicular regression may occur in late pregnancy or even postnatally; these fully virilized male patients have isolated anorchia. Diagnosis of CAH Chromosomal Analysis On initial important evaluation, a chromosomal analysis should be performed with at least 20 metaphases to assess for mosaicism. Results can usually be obtained within 72 hours. Other genetic studies can be performed once a specific diagnosis is being considered. In many centers, fluorescence in situ hybridization of sex chromosome–specific probes can be obtained within 24 hours. This technique accurately counts sex chromosomes, although it cannot detect translocations or some 94 Chapter3: Disorders of sex development

chromosomal fragments; these require a full karyotype on metaphase chromosomes. Hormonal Studies In the absence of palpable gonads, the most likely diagnosis is CAH secondary to 21-hydroxylase deficiency. 17-hydroxyprogesterone (17-OHP) levels should be obtained and will be markedly elevated. Electrolytes should be obtained and monitored closely, as salt wasting may take a few days to develop. Low morning plasma cortisol and high ACTH levels. High plasma renin activity and low aldosterone confirms salt wasting in CAH due to 21-hydroxylase deficiency. If CAH is suspected and 17- OHP levels are not markedly elevated, adrenal precursors should be further evaluated to look for more rare causes of CAH, including, 11- deoxycorticosterone and the ratio of pregnenolone to 17- hydroxypregnenolone are high in 17-α-hydroxylase deficiency; 17- hydroxypregnenolone and DHEA are high in HSD3B2 deficiency, and all steroids are low in lipoid hyperplasia.A high testosterone to DHT ratio suggests a 5-alpha-reductase deficiency. Partial androgen insensitivity syndrome is often a diagnosis of exclusion in a 46, XY patient when none of the tests are revealing. The testosterone may be elevated and, if so, facilitates the diagnosis. However, this is often not the case. Defects in gonadal steroidogenesis are best evaluated after stimulation with hCG (1500 IU intramuscularly on days 1, 3, and 5, with blood drawn on day 6). However, 17- hydroxylase and HSD3B2 deficiencies affect both the gonads and the adrenal cortex and thus are often diagnosed by synacthen stimulation testing. Low levels of all androgen precursors suggests 17α- hydroxylase/17,20 lyase deficiency or a generalized defect in testicular function such as the vanishing testis syndrome or gonadotropin insensitivity. A high ratio of androstenedione to testosterone is indicative of 17-ketosteroid reductase (also called HSD17B) deficiency, and a high ratio of testosterone to dihydrotestosterone is diagnostic of 5α-reductase deficiency. The diagnosis of androgen insensitivity syndrome is suspected when a 46, XY patient has ambiguous or female-appearing external genitalia despite normal or high circulating levels of testosterone and dihydrotestosterone. Blueprint in Pediatric Endocrinology 95

Imaging Studies Ultrasonography usually allows visualization of a neonate's adrenal glands, which may be enlarged in infants with congenital adrenal hyperplasia (CAH); however, normal ultrasonographic findings in the adrenal glands do not exclude a diagnosis of CAH. When adrenal glands are enlarged in patients with CAH, the glands have a cribriform appearance. Ultrasonography also helps identify müllerian structures. In a neonate, findings of ambiguous genitalia, enlarged adrenal glands, and evidence of a uterus are virtually pathognomonic for CAH. Genitography helps determine ductal anatomy. In a neonate with ambiguous genitalia, a catheter can be inserted into the distal urogenital sinus (urethra). Contrast is injected to outline the internal ductal anatomy. Findings may indicate normal urethral anatomy, an enlarged utricle, a müllerian remnant in a male, a common urogenital sinus, or an area of vaginal and urethral confluence in female neonates. CT scanning and MRI are usually not indicated but may help identify internal anatomy. Procedures Diagnostic laparoscopy may be inserted just inferior to the umbilicus under general anesthesia, allowing rapid identification and delineation of the internal duct anatomy without the morbidity associated with open exploration. Biopsy of gonads may be performed laparoscopically by placing additional trocars. Histological analysis of gonadal biopsy specimens may identify ovarian tissue, testicular tissue, ovotestes, or streak gonads. Exploratory laparotomy/gonadal biopsy may help identify internal duct anatomy and allow gonadal tissue to be obtained for histological characterization; however, many authors advocate laparoscopy for this purpose. Medical Management of CAH Child with CAH patient requires replacement of both glucocorticoid and mineralocorticoid, usually with hydrocortisone (12 to 15 mg/m2/day in 2-3 divided doses) and fludrocortisone (usually 0.1 mg/day, but could be as much as 0.3 mg/day in neonates with salt-wasting crises). Neonates with severe salt losing may require sodium chloride supplementation (≤8 mEq/kg/day). Patients with 11β-hydroxylase or 17α-hydroxylase deficiencies have normal aldosterone biosynthesis and require only 96 Chapter3: Disorders of sex development

glucocorticoid. Patients with panhypopituitarism usually require treatment with hydrocortisone, thyroxin, and growth hormone. All male infants with ambiguous genitalia or micropenis in whom rearing as a boy should have a 3-6 months therapeutic trial of monthly depot testosterone injections (25 mg) to attempt to increase the size of the phallus during infancy. This treatment may improve social acceptability of the genitalia later in childhood and adolescence and/or may make reconstructive surgery easier. In cases of suspected partial androgen insensitivity, this treatment will also document the degree to which the patient is androgen responsive and thus may provide useful information on whether rearing as a boy is feasible. Higher doses of testosterone (50- 75 mg every 4 weeks) in infancy may be used under these circumstances. Monitoring During the prepubertal years, children with DSD should have their growth and development monitored. In growing children with CAH, follow-up every three months is recommended. Serum concentrations of adrenal corticosteroids are monitored at some clinics. As they enter the age of puberty, depending on their underlying diagnosis and treatment in early childhood, patients' major issues are generally the initiation of puberty, either with or without intervention. In children who require hormonal treatment to enter puberty, timing is crucial, as once puberty is complete the growth plates fuse and growth ceases. Thus, height and bone age x-rays are important to determine the timing of puberty. Even in children who initiate puberty on their own, the progression and potential need for supplemental hormonal treatment should be routinely evaluated. Considerations for Sex Assignment in CAH In general, the recommended sex assignment should be that of the genetic / gonadal sex, if for no other reason than to retain the possibility of reproductive function. This is especially true for female infants with CAH who have normal internal genital structures and a potential for childbearing. Conversely, genetic male infants with completely female-appearing external genitalia (usually resulting from complete androgen insensitivity syndrome but also seen with severe testosterone biosynthetic defects) should be raised as female because the potential for reconstruction of Blueprint in Pediatric Endocrinology 97

male genitalia is poor. They, too, need to be castrated by early adulthood to avoid malignant transformation of the testes. Male infants with 17-ketosteroid reductase or 5α-reductase deficiency should usually be reared as boys because they have normal levels of androstenedione or testosterone, respectively, and often virilize significantly at puberty. Indeed, many of these patients reassign themselves to the male gender when they are made aware of the diagnosis. . In cultures that value infant boys over girls, parents may strongly resist rearing a female infant with ambiguous genitalia as a girl, and many girls with severely virilized external genitalia will be raised and named as boys. Corrective Surgery . Surgery for female infants with DSD may need to address both an enlarged clitoris and the lack of a vaginal introitus, as well as the presence of a urogenital sinus. The clitoris is normally prominent in many infant girls. Even when enlarged in a girl with virilizing CAH, the clitoris can be prevented from growing larger with adequate suppression of adrenal androgens by glucocorticoid, and it will become less prominent as the patient grows. Thus, mild to moderate clitoromegaly is often best managed without surgery. When attempted, clitoroplasty must be approached keeping in mind the important role of clitoral sensation in the female sexual response. Such surgery must be performed only by experienced operators with scrupulous attention to preservation of clitoral innervations. . Consensus is still lacking regarding the best age for vaginoplasty. Although many surgeons advocate a first procedure in infancy, it is difficult to maintain a functionally adequate introitus in the absence of estrogen exposure and mechanical dilation (with dilators), and many patients require reoperation as young adults. . Hypospadias repair is usually begun in the first year of life, after testosterone treatment (if necessary to increase phallic size). Depending on the degree of hypospadias, more than one surgical procedure may be required. 98 Chapter3: Disorders of sex development

. Intra-abdominal testes are at increasing risk of malignant transformation with time. In a boy with cryptorchidism who is being reared as male, orchidopexy should be performed as quickly as possible; this will also maximize the possibility of fertility when the underlying condition does not preclude it. Dysgenetic gonads that cannot be brought into the scrotum should be removed soon after diagnosis because the risk of malignant transformation in childhood is relatively high. . Patients with persistent müllerian duct syndrome have a reduced but still appreciable potential for fertility, and virilization is unaffected. Thus, the testes should be removed only if they cannot be brought into the scrotum. Because the müllerian and Wolffian structures are closely approximated in these patients, surgical excision of the uterus and fallopian tubes may result in ischemic and/or traumatic damage to the vasa deferentia and testes, and thus salpingectomy and hysterectomy are indicated only in patients whose müllerian structures limit intrascrotal placement of the testes. Prenatal Treatment of CAH In the case of virilizing forms of CAH (particularly 21-β- hydroxylase deficiency), the mother of an affected female fetus can take dexamethasone (20 μg/kg/day), which can cross the placenta and suppress the fetal adrenal gland, thus reducing secretion of androgens and ameliorating virilization of the external genitalia. To be most effective, this treatment should be started by the sixth week of gestation, before the sex or genotype of the fetus is known.

. Although effective in reducing prenatal virilization, this dose of dexamethasone can cause Cushing's syndrome in the mother, and the long-term sequelae of this treatment in the fetus are not known. Therefore, many endocrinologists believe that this treatment should be used only under approved research protocols that allow for case registries and long-term follow-up.

Dysmorphic Syndromes with DSD . Smith-Lemli-Opitz syndrome is an autosomal recessive multiple congenital malformation and mental retardation syndrome caused by a deficiency of 7-dehydrocholesterol reductase. The original description was of microcephaly, mental retardation, hypotonia, incomplete Blueprint in Pediatric Endocrinology 99

development of the male genitalia, short nose with anteverted nostrils, and pyloric stenosis. . Antley-Bickler syndrome is a homozygous or compound heterozygous mutation in the gene encoding cytochrome P450 oxidoreductase (POR) on chromosome 7 q11.2 can cause The physical features of the syndrome are midface hypoplasia, choanal stenosis or atresia, multiple joint contractures, and visceral anomalies (particularly of the genitourinary system). . Camptomelic dysplasia is a 46; XY individuals with mutations in the SOX9 gene may have a skeletal dysplasia, commonly lethal, combined with DSD or female genitalia due to gonadal dysgenesis. The characteristic skeletal deformity is severe anterior bowing of both tibiae. . Other syndromes include Trisomy 13, Trisomy 18, Meckle- Gruber, Ellis-Van Creveld, Aarskog, Camptomelic dwarfism, Carpenter, CHARGE and VACTERL associations. Key Points . Gender assignment by the physician and family may not correlate with gender preference by the patient in adulthood. . The most important sex organ is the brain, which may undergo hormonal imprinting in utero. . The ideal management method is a team approach including neonatologists, religious counselors, geneticists, endocrinologists, surgeons, and ethicists. . The treatment that would be in the best interests of the child would need to fulfill six ethical principles, minimization of physical harm to the child, minimization of psychosocial harm to the child, maximizing the chance of fertility, maximizing opportunities for satisfying sexual relations, if desired, keeping options open for the future and respecting the wishes and beliefs of the parents according to the Islamic rules of marriage and inheritance.

Summary Points . The diagnostic approach to a newborn with DSD involves a multidisciplinary team of pediatric subspecialists include an 100 Chapter3: Disorders of sex development

endocrinologist, geneticist, urologic or pediatric surgeon, and a neonatologist. . Sex is not assigned to the baby until the evaluation has been completed, but as soon as is feasible. . The child is referred to as "baby," not boy or girl. . The family should be encouraged to delay naming the baby until the sex has been assigned . The baby should be evaluated at a centre with expertise in the evaluation of newborns with DSD. . A family history may identify family members with similar problems indicating an autosomal-recessive or X-linked inheritance. . History of infertility, virilization of a female at puberty (5-α- reductase deficiency), or other children born with DSD. Unexplained neonatal death in a male family member could indicate congenital adrenal hyperplasia (CAH) with salt wasting. . Most causes of DSD are due to an autosomal-recessive inheritance, such as CAH, 5-α-reductase deficiency, and defects in testosterone biosynthesis. . X-linked recessive inheritance suggests androgen resistance (the androgen receptor gene is on the X chromosome). . The antenatal history should include questions regarding maternal exposures to androgens, medications, and signs of virilisation in the mother during pregnancy to exclude non-genetic causes of virilisation of the newborn. . The presence of dysmorphic features and/or other congenital anomalies suggests that there may be a syndrome that includes DSD (e.g., Smith-Lemli-Opitz syndrome). . The presence of 1 or 2 gonads effectively rules out a 46, XX DSD, as ovaries do not descend into the inguinal region. A rare exception would be 46, XX Ovotesticular DSD. . The presence of palpable two gonads strongly favors the diagnosis of 46, XY DSD. Blueprint in Pediatric Endocrinology 101

. The presence of only one palpable gonad suggests the diagnosis of mixed gonadal dysgenesis, although it does not rule out a 46, XY DSD. . Normal term male penis is 3.5 ± 0.7 cm. A length of less than 2.5 cm is considered abnormal. . Normal-term female clitoris is less than 1.0 cm. . Micropenis is thus defined as a stretch penile length of less than 2.5 cm in a term male infant, and clitoromegaly as a clitoris greater than 1.0 cm in a term female. In preterm infant males, the penile length is shorter. . Newborns with 46, XX DSD due to CAH may have hyperpigmented labioscrotal folds. . Hypospadias associated with separation of scrotal sacs or undescended testis suggests a DSD. If the urethral opening is at the base of the phallus, it could be a urogenital sinus in a virilized female. This occurs when the urethral and vaginal openings are connected internally and exit at the perineum though a common opening. Clitoromegaly Defined as stretched clitoral length of more than 2.5 standard deviations (SDS) above the mean for age. The mean stretched clitoral length in a full-term newborn female is 1 cm. In a 46, XX infant usually results from excess androgen exposure as occurs in patients with 21- hydroxylase deficiency, 11-hydroxylase deficiency, 3-β-hydroxysteroid dehydrogenase deficiency, placental aromatase deficiency, oxidoreductase deficiency, ovotesticular DSD, testicular DSD and maternal androgen exposure. In a 46, XY infant usually results from defects in testosterone synthesis or action. Differential diagnoses include; defect in testicular testosterone biosynthesis, 17α-HSD deficiency, 5α-reductase deficiency, congenital lipoid adrenal hyperplasia (StAR), Leydig cell hypoplasia (LH receptor mutation), LH deficiency and androgen insensitivity syndrome. Micropenis Micropenis is defined as a stretched penile length of less than 2.5 standard deviations (SDS) below the mean for age. The mean stretched penile length in a full-term newborn male is 3.5 cm. Measurements of 102 Chapter3: Disorders of sex development

less than 2.5 cm (2.5 SDS below the mean) in a full-term newborn male meet the definition of micropenis and warrant evaluation. Penile growth is essentially linear during mid-to-late gestation.

. Penile length in centimeters = 2.27 + 0.16 X (gestational age in weeks)

Although micropenis can be considered a form of DSD, the presence of a normal scrotum and palpable testes indicates a high probability of normal male karyotype. If the testes are not palpable, the penile urethra is absent, or both, the examination better described as ambiguous, and an evaluation and counseling for disorders of sexual development should be performed. After the first few years of life, the penis grows very little until puberty when testosterone levels begin to rise. Occasionally, older boys are brought to physicians for evaluation because of concerns of small genitalia. These boys are usually prepubertal and obese. Most often, these individuals have normal penis size based on stretched penile length, and the apparent smallness is secondary to the penis being concealed in the suprapubic fat pad. However, if the penis does measure less than 2.5 SDs below the mean (approximately 4 cm), further evaluation is indicated. Fetal production of testosterone and its peripheral conversion to dihydrotestosterone (DHT) is necessary for normal male development. Early in gestation, placental human chorionic gonadotropin (hCG) stimulates the developing testes to produce testosterone through binding to the luteinizing hormone (LH) receptor. By approximately 14 weeks' gestation, the fetal hypothalamic-pituitary-gonadal axis is active, and testosterone production falls under the influence of fetal LH. Therefore, penile growth after the first trimester depends on fetal testosterone production. Testosterone is peripherally converted by the enzyme 5-alpha reductase to the more potent androgen DHT, which is responsible for virilization of the male external genitalia. Finally, intact peripheral androgen receptors are necessary for normal male development. Shortly after birth, gonadotropin (LH and FSH) and testosterone production decrease. Beginning at about age 1 week, gonadotropin and testosterone levels begin to rise again to pubertal levels, peaking at age 1-3 months, and then decreasing to prepubertal Blueprint in Pediatric Endocrinology 103

levels by age 6 months. After age 6 months, the little subsequent penile growth that occurs parallels general somatic growth. At the onset of puberty penis growth resumes because of increases in testosterone production. Growth hormone also plays a role in penis growth because micropenis has been observed in children with isolated growth hormone deficiency.

Fig. (3-5): Showing child with micropenis. Causes Micropenis may be caused by a defect anywhere along the hypothalamic-pituitary-gonadal axis, a defect in peripheral androgen action, isolated growth hormone deficiency, or a primary structural anomaly or it may be part of a genetic syndrome. The most common cause of micropenis is abnormal hypothalamic or pituitary function. In the absence of normal hypothalamic or pituitary function, a normally shaped penis may develop due to maternal hCG effect on fetal testosterone production, but adequate penile growth does not occur after 14 weeks' gestation when testosterone production depends on intact fetal pituitary LH secretion. Failure of adequate testosterone production toward the end of gestation due to a primary testicular disorder (Anorchia, testicular hypoplasia) can result in inadequate penis growth. Micropenis can be associated with Septo-optic dysplasia (SOD) which includes the triad of absent septum pellucidum, optic nerve hypoplasia, and hypopituitarism. Micropenis can also occur in children with LH- receptor defects and defects in testosterone biosynthesis (e.g., 17-β- hydroxysteroid dehydrogenase deficiency). The genitalia of individuals with LH-receptor defects vary from a normal female appearance to a 104 Chapter3: Disorders of sex development

male with micropenis. Patients with 17-β-hydroxysteroid dehydrogenase deficiency most often have female-appearing genitalia and, less often, ambiguous genitalia. Defects in peripheral androgen action include 5- alpha reductase deficiency (failure of conversion of testosterone to DHT) and partial androgen insensitivity syndrome (PAIS) due to an androgen receptor defect. However, most children with these conditions have varying degrees of incomplete labioscrotal fusion, resulting in hypospadias and genital ambiguity. Lastly, a genetic syndrome in which micropenis may be a feature includes Prader-Willi, Klinefelter, and Noonan syndromes, and others. When micropenis is associated with hypopituitarism and hypoadrenalism, the infant can develop hypoglycemia, electrolyte abnormalities, hypotension, and shock. Infants with midline defects and those with optic nerve hypoplasia or aplasia deserve particular attention because these defects may point to pituitary hormone deficiencies. Failure to recognize this association in an ill neonate can result in death. Infants who survive the newborn period may exhibit varying degrees of poor growth and failure to thrive, depending on potential associated hormone deficiencies or genetic syndrome. Some other syndromes are associated with micropenis including, CHARGE syndrome (coloboma, heart disease, choanal atresia, retarded growth and development, genital anomalies and hypogonadism, ear anomalies and deafness), Robinow syndrome (hypergonadotropic hypogonadism, cryptorchidism, and hypoplastic genitalia, flat facial profile with prominent nares, hypertelorism, low-set ears, short forearms, rib abnormalities, and spinal abnormalities) and Rud syndrome (hyposmia, developmental delay, congenital ichthyosis, epilepsy, and short stature) . Neonatal hypoglycemia, in the first 24 hours of life, is associated with panhypopituitarism, growth hormone deficiency, and adrenal insufficiency. Other features that may be associated with hypopituitarism during the neonatal period include breech delivery, optic nerve hypoplasia or aplasia, nystagmus, midline defects, and prolonged direct hyperbilirubinemia. . An abnormal sense of smell (anosmia or hyposmia) suggests Kallmann's syndrome. Blueprint in Pediatric Endocrinology 105

. Family history of similarly affected children could suggest a familial form of hormonal deficiency (autosomal recessive), defect in steroidogenesis (autosomal recessive), or androgen insensitivity (X- linked). . Family history of unexplained death in the first year of life could also suggest pituitary hormone deficiencies, adrenal insufficiency, or both. . The proper technique for measuring the penis is to use a rigid ruler held firmly against the symphysis pubis at a right angle. . Firm but gentle traction is placed on the penis to stretch it upward along the ruler to the point of increased resistance. One or both testes may be abnormally descended because testosterone also plays a role in testicular descent. Laboratory Studies . Chromosomal analysis is recommended to confirm chromosomal sex and to evaluate for associated genetic syndromes. If Prader-Willi syndrome is suspected, chromosomal analysis looking for a 15q11-13 band deletion of the paternally derived chromosome (70%), maternal uniparental disomy (25%), or methylation-specific paternal defect (5%) should be undertaken. . Gonadotropin (LH and FSH) reach pubertal levels in healthy male infants, peaking at age 1-3 months. Excessively high or low values during this time help to narrow the differential diagnoses. . Testosterone and DHT levels and their ratio, before and after hCG stimulation, can be measured to evaluate the responsiveness of the testes to gonadotropin stimulation and for 5-α- reductase deficiency (indicated by an increased testosterone-to-DHT ratio). . GnRH-stimulation test can be performed to evaluate the pituitary gland's ability to respond and produce LH and FSH. . In infants suspected hypopituitarism, growth hormone levels can be measured after glucagon stimulation. . Patients with micropenis might rarely have defects in steroid biosynthesis, but instead they often have low levels of gonadotropin (Hypogonadotropic hypogonadism). Because gonadotropins are usually 106 Chapter3: Disorders of sex development

higher in neonates than in older children, these levels can be measured directly. If they are low, or if there is any history of hypoglycemia, pituitary function should be completely evaluated by measuring thyroid- stimulating hormone and thyroxin, as well as cortisol, in a random blood sample (ACTH may also be measured, but it often takes longer for results to be returned). If the cortisol level is equivocal, a low-dose (1 μg/1.73 m2) synacthen stimulation test may be performed. This test differs from the synacthen stimulation test used to diagnose adrenal steroidogenic defects by using a more physiologic dose of synacthen that can detect mild atrophy of the adrenal cortex resulting from chronic deficiency of ACTH. Growth hormone cannot be measured accurately in random blood samples unless the patient is hypoglycemic, but levels of insulin-like growth factor-1 (IGF-1) and IGF-binding protein 3 are readily measured surrogates; growth hormone can be measured after appropriate stimulation if suspicion of growth hormone deficiency is high. Any patient with suspected hypopituitarism should have magnetic resonance imaging of the head and an ophthalmologic examination to look for associated abnormal development of the optic nerves (septo-optic dysplasia). Patients with hypogonadotrophic hypogonadism should have normal testicular function documented with hCG stimulation test. Imaging Studies In situations of genital ambiguity, pelvic ultrasonography is often helpful. The presence of a uterus and ovaries strongly suggests a virilized female (46, XX) infant. When hypopituitarism is suspected, MRI of the head should be obtained to evaluate the hypothalamic and pituitary areas. In Kallmann syndrome, abnormalities of the olfactory system may be seen. Treatment Testosterone therapy in the form of 3-6 monthly intramuscular (IM) injections has been used to increase penis size in infants, children and adolescents. Testosterone Doses . Infants: 25 mg IM monthly for 3-6 doses . Children: 50 mg IM monthly for 3-6 doses Blueprint in Pediatric Endocrinology 107

Adolescents with male hypogonadism, initiation dose of puberty of 40-50 mg/m2/dose as intramuscular depot injection every month. Terminal growth phase dose of 100 mg /m2 /dose as intramuscular injection every month. Maintenance virilizing dose of 100 mg/ m2 /dose, intramuscular every 2 weeks.

Prognosis The prognosis of boys with micropenis secondary to gonadotropin or testosterone deficiency is usually good. These individuals generally respond well to testosterone therapy and function normally as adults. Despite the potential for near-normal adult phallic size and sensitivity, infertility is generally expected. Prognosis is much more guarded in children with androgen insensitivity, especially with significant genital ambiguity. Hypospadias It occurs at a rate of 1 case per 300 live male births; in less than 1% of patients, hypospadias occurs in combination with undescended testes. Clinicians should suspect the possibility of DSD in patients with both hypospadias and cryptorchidism. Cryptorchidism / Retractile Testicles Is the absence of one or both testes from the scrotum. It is the most common birth defect regarding male genitalia. About 3% of full-term and 30% of premature infant boys are born with at least one undescended testis. However, about 80% of cryptorchid testes descend by the first year of life (the majority within three months), making the true incidence of cryptorchidism around 1% overall. A testis absent from the normal scrotal position can be found anywhere along the "path of descent" from high in the posterior (retroperitoneal) abdomen, just below the kidney, to the inguinal ring; found in the inguinal canal; ectopic, that is, found to have "wandered" from that path, usually outside the inguinal canal and sometimes even under the skin of the thigh, the perineum, the opposite scrotum, and femoral canal; found to be undeveloped (hypoplastic) or severely abnormal (dysgenetic); found to have vanished (also see anorchia).About two thirds of cases without other abnormalities are unilateral; one third involves both testes. In 90% of cases an undescended testis can be 108 Chapter3: Disorders of sex development

palpated in the inguinal canal; in a minority the testis or testes are in the abdomen or nonexistent (truly "hidden"). Undescended testes are associated with reduced fertility, increased risk of testicular germ cell tumors and psychological problems when the boy is grown. Undescended testes are also more susceptible to testicular torsion and infarction and inguinal hernias. To reduce these risks, undescended testes are usually brought into the scrotum in infancy by a surgical procedure called an orchiopexy. Although cryptorchidism nearly always refers to congenital absence or maldescent, a testis observed in the scrotum in early infancy can occasionally "reascend" (move back up) into the inguinal canal. Causes . Children might have abnormalities in the pathways/signaling of testosterone, müllerian inhibiting substance, insulin-like 3 hormone or its receptor LGR8, epidermal growth factor and /or estrogens. . Environmental or maternal toxins such as environmental estrogens, phthalate esters, smoking and pesticides have all been linked to increased risk of cryptorchidism, as has maternal alcohol consumption. . Genetic causes are up to 23% of cases have been associated with familial clustering, suggesting an underlying genetic mutation as the etiology in these patients. Mutations in insulin-like growth factor -3 and its receptor, LGR8, have been demonstrated in a small number of cases. . Mechanical problems with development of the gubernaculum, a patent processus vaginalis or impaired intra-abdominal pressure have also been hypothesized to contribute to cryptorchidism. . Neuromuscular: abnormalities of the genitofemoral nerve's calcitonin gene-related peptide or the cremasteric nucleus have been postulated to cause cryptorchidism Cryptorchidism is generally noted on routine physical examination, but patient and/or parents should be questioned regarding history of palpable testes on previous examinations, presence of testes at times when the patient is relaxed, such as when in the bath (may suggest excessive cremasteric reflex or retractile testes) and previous inguinal surgery (iatrogenic cryptorchidism). A family history may be present. Blueprint in Pediatric Endocrinology 109

Examination Examination should take place in a supine position. The patient should be warm and as relaxed as possible. Presence or absence of the testes, position and size of each testis should be noted, as well as the presence of an asymmetric or hypoplastic scrotum and any surgical scars in the inguinal or scrotal region. Physical examination should include inspection and documentation of location of the urethral meatus (specifically looking for hypospadias). Assessment for penile length of less than 2 standard deviations below normal for age, Examination of secondary sex characteristics / pubertal signs for patients presenting with cryptorchidism at an older age. Investigations Imaging is rarely required, but may be sometimes ordered by the surgeon for preoperative planning for unilateral or bilateral non-palpable testes or when physical examination is difficult secondary to body habitus or lack of patient cooperation. Importantly, ultrasound, CT and MRI all have reports of false-negative results, with gonad present at the time of surgical exploration despite being labeled as absent by imaging. Because of the risk of malignant degeneration, most urologists recommend surgical exploration for non-palpable testes despite negative imaging studies. Ultrasound is reliable in identifying testes distal to the internal inguinal ring, but generally is not required as it does not alter therapy. CT scan is no longer recommended because of the risk of ionizing radiation combined with unacceptably high false-positive and false-negative rates. HCG Stimulation Test This is rarely required. If both testes are truly non-palpable, the patient should undergo hCG stimulation test to determine the presence or absence of functioning testes. The hCG stimulation test demonstrates no increase in plasma testosterone after stimulation when testes are absent, with positive and negative predictive values of 89% and 100%, respectively. Patients with bilateral absent testes should be referred for further endocrine and/or genetic evaluation.

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Treatment The mainstay of treatment for cryptorchidism is surgical placement of the testicle(s) into the dependent portion of the scrotum. The optimal timing for surgical therapy is debated, but data suggest there may be better preservation of spermatogenesis and hormonal production with decreased risk of testicular cancer when performed early, ideally prior to age of 2 years, with some suggesting before 1 year of age. A randomized study demonstrated higher testicular volume by ultrasound in those boys randomized to orchiopexy at 9 months compared to 3 years of age. . The use of hormonal therapy (human chorionic gonadotrophin or gonadotrophin-releasing hormone as first-line treatment for cryptorchidism is no longer recommended. The major issues related to treatment include surgical complications such as anesthesia-related, wound infection, hematoma, reactive hydrocele and testicular atrophy. Retractile Testicle(s) A retractile testis is located in a suprascrotal position, but that can be pulled down without pain into the scrotum and remains there after traction are released. This is considered a normal variant in position and these patients generally do not undergo treatment, but should be followed for acquired cryptorchidism and/or reduced testicular volume, which could prompt treatment. Annual follow-up examination is indicated. If cryptorchidism or testicular asymmetry is found at subsequent annual examination, further surgical intervention is required. Patients with ascending testes that can no longer be brought down into the dependent portion of the scrotum and/or testicular asymmetry should proceed to orchiopexy as outlined for patients with palpable undescended testes. References and Further Reading

1. Consensus statement on management of 21-hydroxylase deficiency from the Lawson Wilkins Pediatric Endocrine Society and the European Society for Paediatric Endocrinology (2002) Journal of Clinical Endocrinology and Metabolism 97(9), 4048–4053. 2. Forest, M.G. & Duncharme, J.R. (1993) Gonadotrophic and gonadal homones. In: Paediatric Endocrinology (eds J. Bertrand, 3. B. Rappaport & P.C. Sizonenko), pp. 100–120. Williams & Wilkins, Baltimore. Blueprint in Pediatric Endocrinology 111

4. Grumbach, M.M. & Conte, F.A. (1994) Disorders of sexual differentiation. In: Williams Textbook of Endocrinology (eds J.D. Wilson, D.W. Foster, H.M. Kronenberg & P.R. Larsen), 9th edn, pp. 1303–1426. W.B. Saunders. 5. Metherell, L.A., Chapple J.P., Cooray S. et al. (2005) Mutations in MRAP, encoding a new interacting partner of the ACTH receptor, cause familial glucocorticoid deficiency type 2. Nature Genetics 37(2), 166. 6. Orth, D.N. & Kovacs, W.J. (1998). The adrenal cortex. In: Williams’ Textbook of Endocrinology (eds J.D. Wilson, D.W. Foster, H.N. Kronenberg & P.R. Larsen), 9th edn, pp. 517–664. W.B. Saunders. 7. Wallace, A.M., Beastall, S.H., Cook, B. et al. (1986) Neonatal screening for congenital adrenal hyperplasia: a programme based on a novel direct radioimmunoassay for 17 hydroxyprogesterone in blood spots. Journal of Endocrinology 108, 299–308. 8. Ahmed, S.F. & Hughes, I.A. (2002) The genetics of male undermasculinisation Clinical Endocrinology 56, 1–18. 9. Ahmed, S.F., Khwaja, O. & Hughes, I.A. (2000) Clinical and gender assignment in cases of male undermasculinization: the role for a masculinization score. British Journal of Urology 85, 120–124. 10. Grumbach, N.M. & Conte, F.A. (1998) Disorders of sex differentiation. In: Williams’ Textbook of Endocrinology (eds J.D. Wilson, D. 11. W. Foster, H.M. Kronenberg & P.R. Larsen), 9th edn, pp. 1303– 1426. W.B. Saunders.

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Chapter 4

Reproductive Disorders

. Introduction . Normal pubertal development . Physiology of Puberty . Puberty onset . Physical changes in boys during Puberty o Testicular size, function, and fertility o Pubic hair o Voice change o Male musculature and body shape o Body odor and acne . Physical changes in girls during pubrty o Breast development o Pubic hair o Vagina, uterus and ovaries o Menstruation and fertility o Body shape, fat distribution, and body composition o Body odor and acne . Precocious Puberty . Sequelae of precocious puberty . Causes of central (GnRH dependent) . Environmental & genetic factors influencing HPG axis activation . Peripheral precocious puberty . McCune-Albright Syndrome (MAS) . Variation of normal pubertal development o Premature pubarche o Premature Thelarche . Investigations of precocious puberty . Management of precocious puberty o GnRH agonist . Treatment of peripheral precocious puberty o Cyproterone acetate (Androcur) o Medroxyprogestrone acetate (Depo-Provera) . Complications of peripheral precocious puberty . Delayed puberty 113 114 Chapter 4: Reproductive Disorders

. Hypogonadotropic hypogonadism . Constitutional Delay of Growth and Puberty . Hypothalamic-pituitary disorders . Hypergonadotrophic hypogonadism o Turner's syndrome o Klinefelter's syndrome . Investigations of delayed puberty . Treatment of delayed puberty . Pubertal induction . Polycystic Ovarian Syndrome (PCOS) . Hirsutism . Ferriman-Gallwey score for hirsutism . Investigations of Hirsuitism . Treatment of Hirsuitism . Gynecomastia o Neonatal gynaecomastia o Pubertal gynaecomastia . Causes of elevated estrogen levels or activity . Causes of testosterone deficiency . Causes of impaired testosterone action . Diagnosis and treatment of Gynecomastia

Introduction Puberty is an interval characterized by the acquisition of the secondary sexual characteristics, accelerated linear growth, increase in the secretion of sex hormones, maturation of gonads (testes in boys; ovaries in girls), and the potential for reproduction. It is typically completed within 2 to 5 years. First stage of puberty in girls is the breast development (Thelarche) which may be unilateral for several months, and begins with an elevation of the breast and papilla, and a slight enlargement of the diameter of the papilla (stage 2) defined as breast bud. . Caution must be exercised in examination of the breast tissue in obese girls, as simple fat may be mistaken for breast tissue In males, the onset of puberty is marked by testicular enlargement. Testicular volume established by comparison with ellipsoids of known volume (Prader's orchidometer), is typically > 4 ml. in both sexes, followed by appearances of axillary and pubic hair (Adrenarche / pubarche) and finally menstrual bleeding in females (Menarche) and spermatogenesis (spermarche) in males. These features evolve from appearance to adulthood, and are rated into 5 stages according to Tanner's criteria. Pubertal development appears to begin up to one year in advance in white and up to 2 years in black girls with respect to previous reports. A variety of environmental and genetic factors are involved in the regulation of menarche. In boys, the timing of puberty does not seem to have changed, and is considered normal when it occurs after 9 and before 14 years of age. Pubertal growth spurt occurs during stages 3 to 4 of puberty in most boys, and is completed by stage 5 in more than 95% of them. In girls, pubertal growth spurt occurs during stages 2 and 3. In males, growth velocity can be as low as 3.5 cm/year before puberty and increases from 5 cm/yr on average to 7 cm / year during the first year of puberty, and is approximately 9 cm / year during the second year. Females do not show such a low growth velocity as males before puberty and increase their growth velocity to 6 cm / year during the first year of puberty, and to 8 cm / year on average during the second year.

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Fig. (4-1): Showed Pubertal Tanner Staging. Tanner staging: A, genital rating standards in boys; B, pubic hair rating standards in boys; C, breast rating standards in girls; D, pubic hair rating standards in girls adapted from Marshall WA, Tanner JM. Arch Dis Child. 1970; 45:13-23; Marshall WA, Tanner JM. Arch Dis Child. 1969;44:291-303 Physiology of Puberty Between early childhood and approximately 8–9 yr of age (prepubertal stage), the hypothalamic-pituitary-gonadal axis is dormant, as reflected by undetectable serum concentrations of luteinizing hormone (LH) and sex hormones (estradiol in girls, testosterone in boys). In this phase, the activity of the hypothalamus and pituitary may be suppressed by poorly characterized neuronal restraint pathways. One to 3 year before the onset of clinically evident puberty, low serum levels of LH during sleep become demonstrable (peripubertal period). This sleep-entrained LH secretion occurs in a pulsatile fashion and probably reflects endogenous episodic discharge of hypothalamic gonadotropin-releasing hormone (GnRH). Nocturnal pulses of LH continue to increase in Blueprint in Pediatric Endocrinology 117

amplitude and, to a lesser extent, in frequency as clinical puberty approaches. This pulsatile secretion of gonadotropin is responsible for enlargement and maturation of the gonads and the secretion of sex hormones. The appearance of the secondary sex characteristics in early puberty is the visible culmination of the sustained, active interaction occurring among hypothalamus, pituitary, and gonads in the peripubertal period. By mid-puberty, LH pulses become evident even during the daytime and occur at about 90- to 120-min intervals. The factors that normally activate or restrain the hypothalamic neurons responsible for GnRH secretion (neurosecretory unit known as the GnRH pulse generator) are unknown. In nonhuman primates, a decline in the γ–aminobutyric acid (GABA)–ergic tone in hypothalamic neurons and the resultant increase in the glutaminergic tone activate the GnRH pulse generator. Several other neurotransmitters are probably involved in humans and other primates. It is clear that GnRH is the primary, if not the only, hormone responsible for the onset and progression of puberty because pubertal development can be reproduced in sexually immature or gonadotropin- deficient animals and humans by pulsed administration of GnRH. Mutations of the GPR54 gene (G protein–coupled receptor gene) cause an autosomal recessive form of hypogonadotrophic hypogonadism. Defects of this receptor-ligand system do not affect GnRH neuronal migration, in contrast to the X-linked hypogonadotrophic hypogonadism of Kallmann syndrome; rather they repair the activity of GnRH-secreting neurons in the hypothalamus. The effects of gonadal steroids (testosterone in boys, estradiol in girls) on bone growth and osseous maturation are critical. Both aromatase deficiency and estrogen receptor defects result in delayed epiphyseal fusion and tall stature. These observations suggest that estrogens, rather than androgens, are responsible for the process of bone maturation that ultimately leads to epiphyseal fusion and cessation of growth. Estrogens also mediate the increased production of growth hormone, which along with a direct effect of sex steroids on bone growth, is responsible for the pubertal growth spurt. The age of onset of puberty varies and is more closely correlated with osseous maturation than with chronological age. In females, the breast bud is usually the first sign of puberty (9-10 year), followed by the 118 Chapter 4: Reproductive Disorders

appearance of pubic hair 6–12 month later. The interval to menarche is usually 2 years. There are, however, wide variations in the sequence of changes involving growth spurt, breast bud, pubic hair, and maturation of the internal and external genitals. In males, growth of the testes (> 4 ml in volume or 2.5 cm in longest diameter) and thinning of the scrotum are the first signs of puberty. These are followed by pigmentation of the scrotum and growth of the penis. Pubic hair then appears. Appearance of axillary hair usually occurs in mid-puberty. In males, unlike in females, acceleration of growth begins after puberty is well under way and is maximal at genital stage 3-4 (typically between 13 and 14 yr of age).

. In males, the growth spurt occurs approximately 2 year later than in females, and growth may continue beyond 18 yr of age, while in females' growth usually ceased 1-2 years post menarche

The onset of puberty is preceded by an increase in the androgens secreted by the adrenal glands. Adrenal androgens (androstenedione, dehydroepiandrosterone and dehydroepiandrosterone-sulfate (DHEA-S) are secreted in small amounts during infancy and early childhood, and their secretion gradually increases with age, paralleling the growth of the zona reticularis. The onset of DHEA-S production from the adrenal zone reticularis leads to the phenomenon of Adrenarche. A role for Corticotrophin releasing hormone (CRH) has also been proposed in the regulation of DHEA production, particularly in the human fetal adrenal. More recently, candidate hormones related to body mass, such as insulin and leptin, have been suggested as the triggers of adrenal growth and Adrenarche. The increase in androgen levels occurring in childhood is responsible for the appearance of body odor, and pubic and axillary hair. Gonadotropin releasing-hormone (GnRH), a decapeptide secreted by neurons located in the basal forebrain and extending from the olfactory bulbs to the mediobasal hypothalamus, is responsible for the gonadotropin secretion by the pituitary gland. After birth their activity is "turned-off" by the low circulating levels of androgens/estrogens released by the gonads, by means of a negative feed-back mechanism. GnRH stimulates the release of LH and FSH from the pituitary which in turn stimulates the gonads. LH and FSH have negative feedback effects on the Blueprint in Pediatric Endocrinology 119

hypothalamus, whereas testosterone and androstenedione produced by the testis, and Estradiol (E2) produced by the ovary, inhibit both the hypothalamus and the pituitary gland. Inhibin, activin, and follistatin are also involved in the modulation of the hypophyseal-gonadal axis function, as inhibin and follistatin inhibit and activin stimulates the expression, biosynthesis, and secretion of FSH. These hormones are synthesized mainly in the gonads. Inhibin is produced by the Sertoli cells in the testis and by ovarian granulosa cells. FSH stimulates the synthesis and secretion of inhibin by the gonads, which in turn are involved in the feedback regulation of FSH secretion. Other hormones undergo significant changes at puberty. Growth hormone, insulin, insulin-like growth factor -1, and its major binding protein "IGFBP-3", normally rise at puberty. The increase in growth hormone and IGF-1 concentrations is probably responsible for most of the metabolic changes observed during puberty, including insulin- resistance, increased β-cell response to glucose, and growth spurt. Puberty takes approximately 2 to 5 years to complete, on average, and provides a growth potential of 25 cm in girls and 30 cm in boys. The sex hormones directly stimulate the growth plate, resulting in the growth spurt. There is also an increase in growth hormone (GH) secretion. Estrogen, either from the ovary or aromatized from testicular testosterone, is the factor that mediates the increased GH response during puberty. Puberty Onset The cause of the GnRH rise is unknown. Leptin might be the cause of the GnRH rise. Leptin has receptors in the hypothalamus which synthesizes GnRH. Individuals who are deficient in leptin fail to initiate puberty. The levels of leptin increase with the onset of puberty, and then decline to adult levels when puberty is completed. The rise in GnRH might also be caused by genetics. A study discovered that a mutation in genes encoding both Neurokinin B as well as the Neurokinin B receptor can alter the timing of puberty. The researchers hypothesized that Neurokinin B might play a role in regulating the secretion of Kisspeptin, a compound responsible for triggering direct release of GnRH as well as indirect release of LH and FSH. 120 Chapter 4: Reproductive Disorders

Physical Changes in Boys During Puberty Testicular Size, Function & Fertility In boys, testicular enlargement is the first physical manifestation of puberty (Gonadarche). Testes in prepubertal boys change little in size from about 1 year of age to the onset of puberty, averaging about 2–3 cm in length and about 1.5–2cm in width (volume less than 4 ml). Testicular size continues to increase throughout puberty, reaching maximal adult size about 6 years after the onset of puberty. After the boy's testicles have enlarged and developed for about one year, the length and then the breadth of the shaft of the penis will increase and the glans penis and corpora cavernosa will also start to enlarge to adult proportions. While 20-25 ml average adult size, there is wide variation in testicular size in the normal population.

Fig. (4-2): Prader Orchidometer for Determination of Testicular Volume.

The testes have two primary functions: to produce hormones and to produce sperm. The Leydig cells produce testosterone, which in turn produces most of the male pubertal changes. Most of the increasing bulk of testicular tissue is spermatogenic tissue (primarily Sertoli and Leydig cells). Sperm can be detected in the morning urine of most boys after the first year of pubertal changes, and occasionally earlier. On average, potential fertility in boys is reached at 13 years old, but full fertility will Blueprint in Pediatric Endocrinology 121

not be gained until 14–16 years of age. During puberty, a male's scrotum will become larger and begin to dangle or hang below the body as opposed to being up tight, to accommodate the production of sperm whereby the testicles need a certain temperature to be fertile. Pubic Hair Pubic hair often appears on a boy shortly after the genitalia begin to grow. The pubic hairs are usually first visible at the dorsal (abdominal) base of the penis. The first few hairs are described as stage 2. Stage 3 is usually reached within another 6 to 12 months, when the hairs are too many to count. By stage 4, the pubic hairs densely fill the "pubic triangle." Stage 5 refers to the spread of pubic hair to the thighs and upward towards the navel as part of the developing abdominal hair. In the months and years following the appearance of pubic hair, other areas of skin that respond to androgens may develop androgenic hair. The usual sequence is: axillary hair, perianal hair, upper lip hair, preauricular hair, periareolar hair, and the beard area. As with most human biological processes, this specific order may vary among some individuals. Arm, leg, chest, abdominal, and back hair become heavier more gradually. There is a large range in amount of body hair among adult males, and significant differences in timing and quantity of hair growth among different racial groups. Facial hair is often present in late adolescence, but may not appear until significantly later. Facial hair will continue to get coarser, darker and thicker for another 2–4 years after puberty. Some men do not develop full facial hair for up to 10 years after the completion of puberty. Chest hair may appear during puberty or years after. "Not all males have chest hair". Voice Change Under the influence of androgens, the larynx grows in both sexes. This growth is far more prominent in boys, causing the male voice to drop and deepen, sometimes abruptly but rarely "over night". Male Body Shape By the end of puberty, adult males have heavier bones and nearly twice as much skeletal muscle. The average adult male has about 150% of the lean body mass of an average female, and about 50% of the body fat. The peak of the so-called "strength spurt", the rate of muscle growth, 122 Chapter 4: Reproductive Disorders

is attained about one year after a male experiences his peak growth rate. Often, the fat pads of the male breast tissue and the male nipples will develop during puberty; sometimes, especially in one breast, this becomes more apparent and is termed gynaecomastia. It is usually not a permanent phenomenon. Body Odor and Acne Rising levels of androgens can change the fatty acid composition of perspiration, resulting in a more "adult" body odor. As in girls, another androgen effect is increased secretion of oil (sebum) from the skin and the resultant variable amounts of acne. Acne cannot be prevented or diminished easily, but it typically fully diminishes at the end of puberty. However, it is not unusual for a fully grown adult to suffer the occasional bout of acne, though it is normally less severe than in adolescents. Some may desire using prescription topical creams or ointments to keep acne from getting worse or even oral medication, due to the fact that acne is emotionally difficult and can cause scarring. Physical Changes in Girls During Pubrty Breast Development The first physical sign of puberty in girls is Thelarche which is usually a firm, tender lump under the center of the areola of one or both breasts, occurring on average at about 9- 10 years of age. By the widely used Tanner staging of puberty, this is stage 2 of breast development (stage 1 is a flat, prepubertal breast). Within six to 12 months, the swelling has clearly begun in both sides, softened, and can be felt and seen extending beyond the edges of the areola. This is stage 3 of breast development. By another 12 months (stage 4), the breasts are approaching mature size and shape, with areola and papillae forming a secondary mound. In most young females, this mound disappears into the contour of the mature breast (stage 5), although there is so much variation in sizes and shapes of adult breasts that stages 4 and 5 are not always separately identifiable. Pubic Hair Pubic hair is often the second noticeable change in puberty, usually within a few months of thelarche. It is referred to as pubarche. The pubic hairs are usually visible first along the labia. The first few hairs are Blueprint in Pediatric Endocrinology 123

described as Tanner stage 2. Stage 3 is usually reached within another 6– 12 months, when the hairs are too numerous to count and appear on the pubic mound as well. By stage 4, the pubic hairs densely fill the "pubic triangle." Stage 5 refers to spread of pubic hair to the thighs and sometimes as abdominal hair upward towards the navel. In about 15% of girls, the earliest pubic hair appears before breast development begins. Vagina, Uterus and Ovaries The mucosal surface of the vagina also changes in response to increasing levels of estrogen, becoming thicker and duller pink in color (in contrast to the brighter red of the prepubertal vaginal mucosa). Whitish secretions (physiologic leukorrhea) are a normal effect of estrogen as well. In the two years following thelarche, the uterus, ovaries, and the follicles in the ovaries increase in size. The ovaries usually contain small follicular cysts visible by ultrasound. Menstruation & Fertility The first menstrual bleeding is referred to as menarche, and typically occurs about two years after thelarche. Most girls experience their first period between 11-13 years, but some experience it earlier than their 11th birthday and others after their 14th birthday. In fact anytime between 8 and 16 is normal. In post-menarchal girls, about 80% of the cycles are anovulatory in the first year after menarche, 50% in the third year and 10% in the sixth year. Initiation of ovulation after menarche is not inevitable. A high proportion of girls with continued irregularity in the menstrual cycle several years from menarche will continue to have prolonged irregularity and anovulation, and are at higher risk for reduced fertility. Body Shape, fat Distribution, and Body Composition During this period, also in response to rising levels of estrogen, the lower half of the pelvis and thus hips widen (providing a larger birth canal). Fat tissue increases to a greater percentage of the body composition than in males, especially in the typical female distribution of breasts, hips, buttocks, thighs, upper arms, and pubis. Progressive differences in fat distribution as well as sex differences in local skeletal growth contribute to the typical female body shape by the end of puberty. On average, at 10 years, girls have 6% more body fat than boys. 124 Chapter 4: Reproductive Disorders

Body Odor & Acne Rising levels of androgens can change the fatty acid composition of perspiration, resulting in a more "adult" body odor. This often precedes thelarche and pubarche by one or more years. Another androgen effect is increased secretion of oil (sebum) from the skin. Acne varies greatly in its severity. A positive correlation between the degree of adiposity and early pubertal development in females has been reported. Conversely, ballet dancers, gymnasts, runners, and other female athletes in whom leanness and strenuous physical activity have coexisted from early childhood frequently exhibit a marked delay in puberty or menarche, and they frequently have oligomenorrhoea or amenorrhea as adults. Pubertal delay is also prevalent in males who are physically very active. These observations support the thesis that the energy balance is closely related to the activity of the GnRH pulse generator and the mechanisms initiating and sustaining puberty, perhaps via hormonal signals, which may include adipokines. Precocious Puberty For many years, puberty was considered precocious in girls younger than 8 years; however, recent studies indicate that signs of early puberty (breasts and pubic hair) are often present in girls (particularly black girls) aged 6-8 years. For boys, onset of puberty before age 9 years is considered precocious. Early onset of puberty can cause several problems. The early growth spurt initially can cause tall stature, but rapid bone maturation can cause linear growth to cease too early and can result in short adult stature. The early appearance of breasts or menses in girls and increased libido in boys can cause emotional distress for some children.

. An increased body mass index (BMI) has been associated with early puberty. In some studies the association is stronger in white girls than in black girls.

. Obesity is not clearly associated with early puberty in boys.

The timing of puberty has a genetic component. A history of early puberty in a parent or sibling is relevant and decreases the likelihood that Blueprint in Pediatric Endocrinology 125

early puberty has an organic cause. Predominant mode of inheritance was autosomal dominant. Types of precocious puberty are mainly; central, true, GnRH dependent which is usually happen in 85-90% of cases (major type), peripheral, pseudo, GnRH independent which is usually happen in 10 – 15 % of cases (minor type) and mixed type which is usually starting with peripheral with secondary activation of central. Premature pubarche/ adrenarche and premature thelarche are two common, benign, normal variant conditions that can resemble precocious puberty but are nonprogressive or very slowly progressive. Premature thelarche refers to the isolated appearance of breast development, usually in girls younger than 3 years; premature pubarche refers to appearance of pubic hair without other signs of puberty in girls or boys younger than 7- 8 years. A thorough history, physical examination, and growth curve review can help distinguish these normal variants from true sexual precocity. Sequelae of Precocious Puberty Children with precocious puberty may be stressed because of physical and hormonal changes they are too young to understand. They may be teased by their peers because of their physical difference. Girls who reach menarche before age 9 -to-10 years may become withdrawn and may have difficulty adjusting to wearing and changing pads. Both sexes, but more in boys than girls, may have increases in libido leading to increased masturbation or inappropriate sexual behaviors at a young age. Early puberty accelerates growth. These children may initially be considerably taller than their peers. Because bone maturation is also accelerated, growth may be completed at an unusually early age, resulting in short stature. Causes of Central (GnRH dependent) . Idiopathic cause which is the major cause in most girls (90 %), while secondary causes are common in most boys (70-80%). The hypothalamic-pituitary-gonadal axis is prematurely activated. . Tumors which include optic and hypothalamic glioma, astrocytoma, ependymoma, pineal tumors, and rarely, primitive endocrine tumors such as a craniopharyngioma. Hamartoma of the tuber 126 Chapter 4: Reproductive Disorders

cinereum are congenital tumors composed of a heterotopic mass of GnRH neurosecretory neurons, fiber bundles, and glial cells that are frequently associated with central precocious puberty, often before 3 years of age. They are often associated with gelastic epilepsy presenting often as giggling episodes and developmental delay. . Hydrocephalus, head injury, previous infections such as meningitis or encephalitis, and neurofibromatosis. . Radiotherapy to the brain. The prevalence of precocious puberty is increased after cranial irradiation for local tumors or leukemia. Moderate radiation doses used for the treatment of brain tumors in children, as opposed to low or high doses, are associated with precocious puberty, with a direct relationship between the age at pubertal onset and therapy. Higher doses are usually associated with gonadotrophin deficiency and a delay in puberty. . Mental retardation in children and prolonged not treated sex steroid exposure are associated with precocious puberty. . Gain-of-function mutations in GPR54, G -protein-coupled receptor are necessary for GnRH activation. Environmental & Genetic Factors Influencing HPG Axis Activation . Genetic factors: If relatives experienced early puberty, the chances are very strong to have early puberty in siblings especially girls. . Obesity: As the rate of childhood obesity has exploded, so has the rate of precocious puberty. This is one of the most widely accepted theories about the rise in early puberty rates. Estrogen and leptin, two important hormones in puberty, are produced by adipose tissues, and many researchers believe puberty in girls is triggered when the body reaches a certain percentage of fat, in combination with other factors. This is one reason many competitive youth athletes experience later puberty than their peers. . Xenoestrogens: are "man-made compounds" that mimic the behavior of natural estrogen in the body. They occur in everything from plastic baby bottles and food storage containers to shampoo, cosmetics, and sunscreen to pesticides and insecticides used in residential and Blueprint in Pediatric Endocrinology 127

agricultural pest control to growth hormones fed to the animals that produce our meat, milk and eggs to the water we bathe in. . Phytoestrogens: Soy-based infant formula, Soy has one of the highest concentrations of phytoestrogens, which are naturally occurring plant estrogens. In adults, phytoestrogens are generally considered neutral or even beneficial, especially from dietary sources. . Sexualized television & media: In one controversial theory, some researchers' claim that exposure to sexualized media may be contributing to the increase in cases of early puberty. It is clear that visual stimuli affect the brain and body chemistry. For example, a photograph of a delicious looking meal causes people to salivate. However, the degree to which media depictions of sex could affect brain and body chemistry is still extremely uncertain and highly controversial. Peripheral Precocious Puberty . Adrenal causes include untreated, poor compliance or non classical form of congenital adrenal hyperplasia (CAH). In females presents with signs of virilization (pubic, axillary hair and clitoromegaly) but no breast development. Other adrenal causes include Cushing's syndrome and an adrenal virilizing tumor. . The locations of HCG-secreting tumors are rare include tumors of the liver (hepatoma, hepatoblastoma) and choriocarcinoma of the gonads, mediastinum, retroperitoneum, or pineal gland. . Tumors of the adrenal gland are rare in childhood. They may occur at any age from infancy into adolescence, and the clinical manifestations of these tumors depend on the type of the hormones they secrete. The most frequent hormonal effects are secondary to androgen secretion, resulting in virilization of girls and early puberty in boys. The primary hormonal picture is rarely that of estrogen effects, which lead to feminization in males and precocious pseudopuberty in females. . Ovarian tumors can be either feminizing or masculinizing. The most common tumor associated with isosexual precocity is the benign ovarian follicular cyst. The cells lining the cysts are luteinized, leading to estrogen production. Granulosa cell tumor is the next most common feminizing neoplasm of the ovary. Juvenile granulosa cell tumors that develop in premenarchal females produce sexual precocity as a 128 Chapter 4: Reproductive Disorders

consequence of estrogen secretion. This may present as premature breast development or vaginal bleeding. Virilization may also be present. These tumors may also secrete HCG. . Sex-cord tumors may have characteristics of both granulosa and Sertoli cells. Masculinizing tumors (Leydig-Sertoli cell tumors or arrhenoblastoma) are unusual before adolescence. These tumors are the most common virilizing ovarian tumor. The masculinizing tumors tend to have abnormal differentiation that leads to an unusual pattern of steroid secretion with androstenedione predominating over testosterone secretion. . Testotoxicosis: The human luteinizing hormone (LH) receptor belongs to the family of G-protein coupled receptors. The molecular defect is a dominant mutation in the LH receptor gene that results in the production of a receptor that is capable of spontaneous activation in the absence of either LH or HCG. . Severe hypothyroidism: This disorder also has been called van Wyk-Grumbach syndrome. The exact mechanism for the development of sexual precocity secondary to hypothyroidism is unknown. It is believed to be secondary to the structural similarity between thyroid-stimulating hormone (TSH) and LH. This is the only form of sexual precocity in which growth may be arrested rather than stimulated. . Exposure to exogenous hormones such as the contraceptive pill or testosterone gels may be responsible for early pubertal development in some patients. Estrogenic agents in cosmetics and food products have also been implicated in causing an earlier age of puberty; 'epidemics' of premature thelarche (isolated breast development) in some geographic areas may be linked to an environmental exposure to estrogens. . Central precocious puberty (CPP) can be considered as GnRH‐driven precocious puberty; the physiology is the same as puberty occurring at the usual age except for age of onset. . Peripheral precocious puberty (PPP) is GnRH‐independent includes all pubertal development that is the result of hormonal stimulation other than hypothalamic GnRH pulsatile release stimulating pituitary gonadotropin pulsatile secretion.

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McCune-Albright Syndrome (MAS) Is a rare, sporadically occurring genetic disorder, result of activation mutation in the gene that codes for the alpha subunit of the stimulatory G protein (Gsα). The exact incidence is unknown. It consists of at least two features of the triad of polyostotic fibrous dysplasia, and autonomous endocrine hyperfunction.The most common form of autonomous endocrine hyperfunction in this syndrome is gonadotropin-independent precocious puberty, but affected individuals also may have hyperthyroidism, hypercortisolism and acromegaly. Non-endocrine abnormalities include hypophosphatemia, chronic liver disease, tachycardia, and, rarely, sudden death, possibly from cardiac arrhythmias.

Fig. (4-3): Café au lait Skin Pigmentation Precocious puberty is more common in girls than in boys. Girls as young as 4 months with MAS can have breast development or vaginal bleeding. A dominant ovarian cyst develops independent of stimulation by gonadotropin. This cyst secretes estradiol, which causes sexual precocity. In addition, excess estrogen exposure often stimulates increased growth velocity and can result in a marked advancement in skeletal maturity. Gonadotropin-independent precocious puberty is far more common in affected girls than in boys. Other manifestations of MAS probably occur equally in both sexes. Fibrous dysplasia can involve any bone but most commonly affects the long bones, ribs, and skull. Fibrous dysplasia ranges from small asymptomatic areas detectable only by bone scan to markedly disfiguring lesions that can result in frequent pathologic fractures and impingement on vital nerves. 130 Chapter 4: Reproductive Disorders

Variation of normal pubertal development

Idiopathic Isolated Premature Adrenarche Common pubertal variant characterized by the early development of pubic hair, axillary hair and odor, and/or acne. It results from increased production of adrenal androgens in both sexes at an earlier than normal age resulting from premature maturation of the zona reticularis of the adrenal cortex. It has been suggested that there is a reduction in 3á- hydroxysteroid dehydrogenase activity and induction of the 17, 20-lyase component of the P450c17 enzyme complex in the zona reticularis. Some subjects with precocious adrenarche have been reported to have heightened androgen receptor gene activity. Finally, etiological or possible roles for corticotropinreleasing hormone, insulin, IGF-1, and leptin have also been proposed. Precocious adrenarche occurs much more commonly in girls than in boys, and appears to develop more often in obese and / or African-American girls. It occurs more often in children with low birth weight. Diagnosis of isolated adrenarche In both girls and boys, there is no clinical evidence of virilization, no growth spurt, increase in muscle bulk, voice-deepening, or temporal hair recession. In addition, affected girls will not manifest clitoromegaly and boys will not have penile enlargement. Furthermore, there is no evidence of ovarian estrogen-mediated components of puberty in girls and no testicular enlargement or function in boys. If a child presents at a very young age, an organic cause is more likely to be found. However, in infant boys with isolated scrotal hair, typically no cause is found and the hair subsequently falls out within 12 months. In most cases of idiopathic precocious adrenarche, serum levels of DHEA and/or DHEAS are in the respective pubertal ranges for girls and boys, and the bone age are mildly advanced. In girls with precocious adrenarche, serum levels of other adrenal steroids are usually normal or only slightly elevated for age, especially if measured after stimulation with ACTH, but normal after leuprolide administration. These observations suggest that precocious adrenarche in girls is associated with functional adrenache hyperandrogenism, but no biochemical evidence of ovarian hyperandrogenism. Yet it has also been demonstrated that girls with precocious adrenarche may have Blueprint in Pediatric Endocrinology 131

ultrasonographic and Doppler evidence of polycystic ovaries with an increase in ovarian volume, small-sized subcapsular follicle number, stromal echogenicity, and stromal vascularization over time. If a child presents with the classical phenotype, no other laboratory or radiological studies are usually warranted, unless there is significant rapidity of progression of symptoms. On rare occasion, children with more serious organic pathologies associated with hyperandrogenism (eg, nonclassical adrenal hyperplasia, adrenal tumors, and gonadal tumors) or true precocious puberty may initially present similarly to those with apparent idiopathic isolated premature adrenarche. Serum measurements of 17- hydroxyprogesterone (basally or after ACTH stimulation) and testosterone (early morning), along with ultrasounds of the adrenals and/or gonads, may need to be done. Isolated adrenarche in girls, measurement of LH, FSH, and estradiol is not indicated. This pubertal variant has been considered to be benign and self-limited, but recent epidemiological and biochemical data suggest that, at least in girls with associated low birth weight and rapid postnatal catch-up growth, precocious adrenarche may be followed by early onset and rapid progression of true puberty as well as by future development of functional ovarian hyperandrogenism / polycystic ovarian syndrome. Treatment No proven treatment for idiopathic precocious adrenarche. Basic practices to limit weight gain, regulate cholesterol intake, and avoid smoking seem advisable. Investigative use of metformin in children with precocious adrenarche has been shown, in small cohorts, to improve body composition and delay the onset of true puberty, Premature Pubarche Premature pubarche refers to the precocious appearance of pubic hair without other signs of puberty or virilization. Appearance of pubic hair in girls may be considered normal when it occurs after 7 years of age in white subjects, and after 6 years of age in African-Americans. Axillary hair, apocrine odor, and acne may or may not be present. Growth velocity may be increased, and slightly advanced bone maturation usually well correlated with the height age, is often present. The transient acceleration of growth and bone maturation has no negative effects on the onset and progression of puberty, and on final height. 132 Chapter 4: Reproductive Disorders

The precise etiology of premature pubarche is not known. Generally, it has been attributed to an early maturation of the zona reticularis of the adrenal cortex leading to an increase of adrenal androgens to levels normally seen in early puberty and, in turn, to the premature appearance of pubarche. Because half of patients have normal androgen levels, a hypersensitivity of the hair follicle to steroid hormones has also been proposed. In patients with isolated premature pubarche in the absence of biochemical and metabolic abnormalities, a hypersensitivity of the pilosebaceous unit to androgens as a result of increased androgen receptor activity may be responsible for the isolated precocious appearance of pubic hair. Premature Thelarche Premature thelarche refers to the precocious appearance of breast development in girls with no other signs of sexual maturation or accelerated growth velocity and bone age advancement. It is most common during the first two years of life. The etiology of premature thelarche is still unknown; some authors postulated that an increase in breast sensitivity to estrogen might be responsible for the premature development of breast tissue. Premature thelarche is usually a self- limited condition that undergoes spontaneous regression during the first 2-3 years of life. However, in some cases the outcome of premature thelarche is not always entirely benign. It is now clear that when its onset occurs after 2-3 years of age, a certain percentage of patients develop central precocious puberty. Laboratory Studies of precocious puberty . Measurement of early morning testosterone levels in boys in early puberty are higher than afternoon levels because luteinizing hormone (LH) and testosterone levels rise with sleep onset in early puberty. . For girls, estradiol measurements are less reliable indicators of the stage of puberty. Many commercial assays are not sufficiently specific or sensitive enough to demonstrate an increase during early puberty. . Levels of adrenal androgens (DHEA, DHEAS) are usually elevated in boys and girls with premature pubarche. DHEA-S, the storage form of DHEA, is the preferred steroid to measure because its levels are much higher and vary much less during the day. Serum 17-OH Blueprint in Pediatric Endocrinology 133

progesterone study if congenital adrenal hyperplasia is suspected. If a random level is within the reference range, the diagnosis can be excluded; however, if the random 17-OH progesterone level is elevated, ACTH stimulation test provides the greatest diagnostic accuracy. . Because of the development of more sensitive third-generation assays for LH, which can detect levels as low as 0.1 IU/l or lower, the random LH is now the best screening test for central precocious puberty (CPP). An LH level of less than 0.1 IU/l is generally prepubertal; Random follicle-stimulating hormone (FSH) levels do not discriminate between prepubertal and pubertal children. Suppressed levels of LH and FSH accompanied by highly elevated testosterone or estradiol levels point suggest precocious pseudopuberty rather than central precocious puberty. . The measurement of baseline estradiol is helpful in distinguishing premature thelarche from precocious puberty, although the differential diagnosis is based on the results of the classic gonadotropin releasing- hormone (GnRH) stimulation test. Baseline LH and FSH plasma levels are often higher, and peak LH levels are significantly and constantly elevated in precocious puberty than in premature thelarche patients, whereas peak FSH levels may not be significantly different in the two groups. A stimulated LH/FSH ratio greater than 1 is suggestive of precocious puberty. . A definitive diagnosis of central precocious puberty may be confirmed by measuring LH and FSH levels 30-60 minutes after stimulation with gonadotropin-releasing hormone (GnRH) at 100 mcg or with a GnRH analog . An increase in LH levels to more than 8 IU/L is diagnostic of central precocious puberty, but this depends on the specific LH assay used. If no increase in LH and FSH levels after the infusion of GnRH suggests precocious pseudopuberty . In certain situations e.g. post-surgery for a craniopharyngioma, following radiotherapy, or in patients with septo-optic dysplasia and holoprosencephaly, should warrant a full pituitary hormone evaluation to look for abnormalities of other anterior and posterior pituitary hormones. 134 Chapter 4: Reproductive Disorders

. Genetic testing should be carried out in patients suspected to have neurofibromatosis type 1, MAS, familial testotoxicosis and gain-of- function mutations in GPR54, a G protein-coupled receptor. . Thyroid function test to rule out primary hypothyroidism, a variant of early puberty. Radiological investigations of precocious puberty . A non-dominant (typically, left) hand / wrist radiograph to estimate skeletal age. The most commonly used method is that of Greulich and Pyle. The bone age is typically advanced in patients with precocious puberty. The bone age may also help predict the estimated adult height range and its relation to the midparental height; caution must be exercised in this interpretation as current standards have been validated in normal children only and not in those with precocious puberty. If bone age is within one year of chronological age, puberty has not started or the duration of the pubertal process has been relatively brief. If bone age is advanced by 2 years or more, puberty likely has been present for a year or more or is progressing more rapidly. . Pelvic ultrasound examination should be undertaken in all girls, where it may reveal the multicystic pattern that is a classic feature of early puberty. Uterine size and shape (infantile, cylindrical) and presence of endometrial echo reflect estrogen effect, while the presence of follicles in the ovaries reflects gonadotrophin stimulation. The uterus at puberty changes in shape from a tubular to a pear-shaped structure. Endometrial thickening suggests that pubertal concentrations of estrogen have been attained, and an endometrium around 6 to 8 mm implies imminent menarche. The sexual precocity in girls with MAS is caused by autonomously functioning multiple, luteinized, follicular cysts of the ovaries with an occasional large solitary cyst. A pelvic ultrasound will help identify gonadal estrogen-secreting tumors. . MRI of the brain helps identify tumors, presence of hydrocephalus, structural hypothalamic-pituitary abnormalities, and midline brain defects. The characteristic appearance of a hamartoma is that of a sessile or pedunculated mass usually attached to the posterior hypothalamus between the tuber cinereum and the mamillary bodies. High-resolution study should focus on the hypothalamic-pituitary area. For healthy girls aged 6-8 years with no signs or symptoms of CNS Blueprint in Pediatric Endocrinology 135

disease, the likelihood of finding a tumor or hamartoma is only about 2%; therefore, this test may be unnecessary depending on the clinical situation. . The younger the child with central precocious puberty, the greater the chance of CNS pathology (among children younger than 6 years). . Boys younger than 9 years, the incidence of CNS findings is much higher than in girls, and MRI should be part of the evaluation.

Management of precocious puberty When central precocious puberty (CPP) is caused by a CNS tumor other than a hamartoma, a resection should be attempted to the extent possible without impinging on vital structures such as the optic nerves. Radiotherapy is often indicated if surgical resection is incomplete. Unfortunately, removal of the tumor rarely causes regression of precocious puberty. Goals of Treatment . Decrease the progression of pubertal changes . Decrease bone maturation . Increase the predicted final adult height . Psychosocial and behavioral therapy The decision regarding commencing treatment is based on several factors, such as age at onset, predicted final height, psychological effects, and rate of progression of puberty. The younger the patient at onset, the more compromised will be final height. Treatment will halt progress of the disease, but regression of already established secondary sexual characteristics is only minimal. Menarche, if already established, will be halted. Parents of girls with learning disability often request treatment, anxious that their daughter will not understand or be able to cope with menstruation. GnRH Agonist Depot Continuous exposure of the GnRH receptor to GnRH agonist suppresses puberty, as it is only the pulsatile exposure that triggers pubertal progression. Synthetic preparations of GnRH agonists are available with a longer half-life than natural GnRH. GnRH agonists are 136 Chapter 4: Reproductive Disorders

the only effective treatment modality for central precocious puberty. However, GnRH antagonist is recently available. GnRH agonists have the paradoxical effect of down-regulating gonadotrophin release when administered in depot form at a high dose. Intranasal preparations have also been used previously, but are now rendered obsolete by the depot preparations. There are 3 available Depot preparations including; Leuprorelin acetate (Lupron) 0.3 mg / kg, Tryptorelin (Decapeptyl) 50-100ug/kg and Goserelin (Zoladex). These preparations are usually given 3-4 weekly depending on the regular follow up of clinical suppression of puberty as well biochemical suppression of gonadotropin, 3- monthly preparations are also available, as Lupron (22.5 mg / vial, Decapeptyl 11.5 mg/ vial and 10.8mg/vial). An implantable GnRH agonist, histrelin, has been used successfully. The implant is effective up to a year, possibly more. The suppression of puberty with these agents is reversible with few adverse effects. The withdrawal of sex steroids following treatment can result in uterine bleeding in girls. It can also result in mood swings and hot flushes. There have been reports of treatment leading to a reduction in bone mineral density (prophylactic vitamin D and calcium intake is advisable), although the long-term effects are not known. Treatment improves the final height of children with rapidly progressing puberty, based on calculation of a predicted final height, particularly in younger children (less than 6 years old).There is only minimally convincing evidence of an improvement in final height in girls 6 to 8 years old; and in those between 8 and 10 years old, GnRH agonists have shown no benefit in final height. There are few results of final height benefit in boys. Growth Hormone (GH) Treatment with GnRH agonists can lead to a reduction in the growth rate due to reduction in GH and insulin-like growth factor 1 (IGF-1) levels. Addition of GH treatment to GnRH agonist therapy may lead to a better growth velocity, although data on an improved final height are not convincing. It may of benefit in adolescent girls who are short and they have starting up their puberty provided that their bone epiphysis not yet closed.

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Cyproterone Acetate (Androcur) This may be used in conjunction with GnRH agonists, or rarely, alone in patients who do not show a clinical response to GnRH agonists. It is a peripherally-acting anti-androgen that suppresses both gonadotrophin and gonadal function. Cyproterone may also be used in the early phase of GnRH agonist therapy to prevent uterine withdrawal bleeding. . Treatment should be stopped around the physiological age of puberty in boys and girls and should not be continued in girls with a bone maturation of more than 12 years. There are limited data available in boys relating to the optimum time to stop treatment based on bone age; however it is advised that treatment is stopped in boys with a bone maturation age of 13-14 years. . Because the risk of osteoporosis, all children receiving these medications should have optimum supplements of daily calcium and vitamin D. . Children who are short, recent clinical trials of combination of both growth hormone and GnRH agonist might have beneficial effects on the final height. . Mood changes, including depression have been reported. Patients with known depression should be monitored closely during therapy.

Medroxyprogestrone Acetate (Depo-Provera) Inhibits secretion of pituitary gonadotropin and inhibits the effect of LH. Effective at slowing the breast growth and preventing or stopping menses when administered every 3 months, although breakthrough bleeding may occur. Relatively inexpensive; consider when Leuprolide cost is a factor and when adult height prediction is close to reference range or is not a major concern. Dose is 150 mg IM every 3 months. GnRH Antagonist GnRH antagonists have been recently introduced in clinical practice. So far, only two of the third-generation GnRH antagonists have been registered: cetrorelix (Cetrotide; Serono) and ganirelix (Orgalutran, Antagon; Organon). So far no comparative studies between GnRH 138 Chapter 4: Reproductive Disorders

antagonists have been performed as treatment of central precocious puberty. Follow-up . For patients with precocious puberty treated with gonadotropin- releasing hormone (GnRH) agonists, follow up every 4-6 months to ensure that progression of puberty has been arrested. . Favorable signs include normalization of accelerated growth, reduction (or at least no increase) in size of breast and suppression of gonadotropin levels after a challenge of GnRH. . GnRH test about 4 months after starting the drug to confirm suppression and then no more often than yearly, as long as clinical indicators suggest that the drug is working as intended. Some clinicians advocate dispensing with formal GnRH testing as long as growth has slowed and pubertal signs are static. . Monitor bone age yearly to confirm that the rapid advancement seen in the untreated state has slowed, typically to a half year of bone age per year or less. . For patients not treated with GnRH agonists, in many cases, the physician may elect to observe the child with central precocious puberty (CPP), either because the age is borderline (7-8 year) and the child and family are coping well or because the progression of puberty is not rapid and the bone age is only mildly advanced (≤ 1 year), predicted adult height falls well within the reference range. . In these cases, follow-up at 3-month intervals is appropriate. Testing and treatment may be initiated if the tempo of puberty begins to accelerate and predicted adult height deteriorates. Prognosis . Most girls with early puberty who are aged 6 to 8 years at the onset of puberty achieve an adult height within the reference range. Treatment with GnRH analogues such as Lupron is usually associated with only a modest gain in final height in this age group. . Most studies show significant improvement in adult height compared with height predicted at the start of therapy, but the extent of Blueprint in Pediatric Endocrinology 139

this improvement depends to some extent on the age of onset of central precocious puberty. . Benefit of GnRH treatment in terms of increased adult height is the greatest in patients who are diagnosed with central precocious puberty and started on GnRH analogues at younger ages. . Normal adult height can be achieved in most cases if treatment is started before bone maturation is too advanced (>12 years in girls, >13 years in boys) and if good gonadal suppression is maintained for several years. Treatment allows growth to continue while dramatically slowing the rate of bone maturation. Key Points . Stimulatory influences, on hypothalamus- pituitary axis which are not well understood, become predominant with the onset of puberty after inhibitory factors have resulted in the relative dormant prepubertal status. . Because the hypothalamic gonadotropin-releasing hormone (GnRH) secreting neurons, the pituitary gonadotropes, and the ovarian component are all capable of adult function at any age, it is apparent that the regulation lies within the complexities of the higher centers of the CNS. . In girls, most cases of central precocious puberty are idiopathic; however, the risk of a tumor or other CNS abnormality is greater in girls younger than 6 years who have rapid progression of puberty or any central nervous system signs or symptoms (headaches, visual disturbances, seizures). . Because some of these tumors are malignant (glioma, astrocytoma), failure to consider this possibility and to perform CT scanning or MRI in high-risk cases could result in delayed diagnosis, increased morbidity, and poorer chance of a cure. . In boys, organic causes of precocious puberty are more likely. CT scanning or MRI of the brain and pituitary gland should be part of the evaluation once the child is diagnosed with central precocious puberty. . The diagnosis of precocious puberty requires documentation of progression of pubertal development and accelerated growth rate. Gonadotropin-releasing hormone (GnRH) stimulation testing may be 140 Chapter 4: Reproductive Disorders

necessary to determine whether precocious puberty is GnRH‐driven (central) or GnRH-independent (peripheral). . Treatment of central precocious puberty is usually with gonadotrophin-releasing hormone agonists. . Peripheral precocious puberty is more difficult to treat; may require ketoconazole, or aromatase inhibitors and anti-androgens. . Treatment should be stopped once an acceptable age of puberty is reached.

Treatment of Peripheral Precocious Puberty Treatment of peripheral precocious puberty is more complicated. Optimum management of disorders such as congenital adrenal hyperplasia (CAH) with hydrocortisone (with or without fludrocortisone) therapy will help prevent rapid virilisation in patients with CAH. Typically, they do not need any further drug treatment. Tumors of the ovary, testes, or adrenals need surgery. HCG tumors are more difficult to treat and patients may need a combination of surgery, chemotherapy, and radiation. Medroxyprogestrone Acetate (Provera) Structurally similar to glucocorticoid. Progestational agent which suppresses gonadotrophin. It is useful in the treatment of both types of precocious puberty. Usually is effective in halting the advancement of secondary characters in both sexes. It is effective in preventing menstruation and there are no effects on bone maturation. Ketoconazole It is more commonly used in treating fungal infections, but may be used in treating precocious pseudopuberty. It inhibits steroid synthesis at the level of 17 α -hydroxylase/17, 20-lyase, a key enzyme in sex steroid production. It also inhibits testosterone binding to its binding globulin. In some cases, especially in those children with markedly advanced bone age, a rapid decrease in sex hormone levels may trigger true central puberty. In this event, add GnRH analogs to the treatment regimen. Dose 400-600 mg/day. Suppression happens within 48 hour with potential hepatotoxicity.

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Aromatase Enzyme Inhibitor Aromatase inhibitors are a second-line treatment to reduce growth rate and bone age advance. Testolactone, a first-generation aromatase inhibitor, inhibits functions of testosterone that are dependent upon its conversion to estrogen. Newer aromatase inhibitors such as anastrozole and letrozole may also be used. If aromatase inhibitors are used, antiandrogen agents may be required to reduce testosterone effects on pubic hair and genital development. These include spironolactone and bicalutamide. Aromatase inhibitors prevent the conversion of androstenedione to estrone and testosterone to estrogen. Because estrogens play a major role in epiphyseal maturation (besides their obvious role in generating female secondary sexual effects), inhibiting estrogen production has salutary effects on slowing the progress of precocious pseudopuberty. Adjunctive use of GnRH analogs may be required if true central puberty occurs as a complication of treatment Androgen Antagonists Cyproterone Acetate: Dose of (70-150 mg/m2/day divided into 2 doses) halted the progression of pubertal signs. It has similar structure to cortisol, might result in Cushingoid features and suppresses the ACTH- Adrenal axis. Spironolactone (Aldactone): mainly used as a diuretic. It is also a weak competitive androgen antagonist. Other properties include inhibition of 17 α –hydroxylase, 17, 20-lyase and interference with testosterone binding to sex hormone binding globulin. It is typically used to treat precocious pseudopuberty in conjunction with another drug (e.g., an aromatase inhibitor). Nonsteroidal androgen antagonists (flutamide): Are more effective; however, they also carry greater hepatotoxicity. As noted above, adjunctive use of GnRH analogs may be required if true central puberty occurs as a complication of treatment. Antiestrogens Estrogen receptor blockers (e.g., Tamoxifen, Raloxifen) may be an alternative to aromatase inhibitors and progestins in the treatment of McCune-Albright Syndrome in girls or in precocious pseudopuberty associated with excess estrogen secretion from ovarian cysts. 142 Chapter 4: Reproductive Disorders

Tamoxifen is competitively binds to estrogen receptor, decreases DNA synthesis and inhibits estrogen effects. This drug is currently being tested in clinical trials in children; dose of 10-30 mg orally daily is effective in controlling estrogenic affects in McCune-Albright syndrome. . Children with McCune-Albright syndrome and testotoxicosis (familial male limited) need pharmacotherapy to prevent the synthesis or action of gonadal steroids. . Pharmacotherapeutic options include ketoconazole, Cyproterone, aromatase inhibitors (e.g., testolactone, letrozole, anastrozole), and antiandrogen agents (e.g., spironolactone, bicalutamide). Long term complications of peripheral precocious puberty McCune-Albright syndrome, the long-term complications results from the multiple endocrinopathies that these patients may develop. Patients may also develop extremely deforming and disabling polyostotic bone changes. There are many successful therapeutic trials of bisphosphonate therapy for their bone deformities. Testotoxicosis complications are related to early sexual and physical maturation. Other complications are psychological and related to the early sexual and physical maturation. Congenital adrenal hyperplasia complications from overtreatment with hydrocortisone (poor growth, adrenal suppression, features of Cushing syndrome) may be observed. Under treatment of females may result in irreversible virilization and polycystic ovarian syndrome. Untreated or poorly treated CAH may develop testicular adrenal rest tumor, responsive to glucocorticoid suppression. Subfertility may be associated with CAH in both males and females. Adrenal tumors are more common in patients with CAH than in the general population. Delayed Puberty It is defined as the absence of breast development by the age of 13 years in girls or in a boy testicular volume of less than 4 ml by age of 14 years. Abnormal pubertal development may be due to functional or structural deficiencies of the hypothalamic-pituitary-gonadal (HPG) axis. Blueprint in Pediatric Endocrinology 143

. Pubertal delay is more commonly seen in boys than girls and the great majority of boys will be eventually diagnosed with constitutional delay of puberty (CDP). Hypogonadism manifests differently in males and in females before and after the onset of puberty. If onset is in prepubertal males, the individual has features of eunuchoidism, which include sparse body hair, poor development of skeletal muscles, and delay in epiphyseal closure, resulting in long arms and legs. In females with hypogonadism before puberty, failure to progress through puberty or primary amenorrhea is the most common presenting feature. Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. . Abnormalities within the hypothalamus or pituitary lead to hypogonadotrophic hypogonadism whereas primary gonadal failure is characterized as hypergonadotropic hypogonadism. Hypogonadotropic Hypogonadism Causes . Congenital o Isolated GnRH deficiency o Kallmann‘s syndrome . KAL1, FGFR1, PROKR2 . Idiopathic hypogonadotropic hypogonadism o GnRHR,FGFR1,GPR54, Leptin, FSHα-subunit, LH α- subunit mutations . Idiopathic hypogonadotropic hypogonadism o Associated with obesity o Leptin, Leptin receptor, PC1mutations . Adrenal hypoplasia congenital (AHC) . Pituitary transcription factor deficiency . Syndromes 144 Chapter 4: Reproductive Disorders

o Prader-Willi syndrome o Noonan syndrome o CHARGE syndrome o Bardet-Biedl syndrome Acquired . Suprasellar/sellar solid tumors o Craniopharyngioma . Trauma/surgery . Infiltration o Hypophysitis o Lymphocytic o Granulomatous . Histiocytosis X, Wegener and Sarcoidosis. . Infectious—meningoencephalitis It results from failure of the hypothalamic GnRH pulse generator or from inability of the pituitary to respond with secretion of LH and FSH. Hypogonadotropic hypogonadism could be attributed to a variety of congenital origins including single gene mutations, idiopathic forms, and genetic syndromes. Acquired causes of hypogonadotrophic hypogonadism include central nervous system (CNS) insults such as trauma, irradiation, and intracranial tumors. By far the most common cause of hypogonadotrophic hypogonadism is transient, and is termed constitutional delay of growth and puberty. It may be observed as one aspect of multiple pituitary hormone deficiencies resulting from malformations (e.g., septo-optic dysplasia, other midline defects) or lesions of the pituitary that are acquired postnatally. In 1944, Kallmann described familial isolated gonadotropin deficiency. Recently, many other genetic causes have been identified. Hypogonadotropic hypogonadism, in which the sense of smell is not disrupted, has been associated with mutations in GNRH1, KISS1R, GNRHR, TAC3 and TACR3 genes. Kallmann syndrome (anosmic hypogonadotrophic hypogonadism) has been associated with mutations Blueprint in Pediatric Endocrinology 145

in KAL1, FGFR1, FGF8, PROK2, and PROKR2 genes. The relationship with Kallmann syndrome is thought to be because these genes are all related to the development and migration of GnRH neurons. All patients with Kallmann syndrome have either anosmia or hyposmia (reduced sense of smell), and may also exhibit unilateral renal agenesis, atrial septal defect, colorblindness, and synkinesia (mirror movements). The sense of smell can easily be confirmed by testing the recognition for common substances such as alcohol or coffee.

Fig. (4-4): Showed Relationship of Olfactory Bulb & GNRH Neurons. Other conditions that affect hypothalamic development and cause hypogonadotrophic hypogonadism include Prader-Willi syndrome, which is a result of paternal deletions, methylation defects, and maternal uniparental disomy of imprinted loci on chromosome 15q12. Children with this syndrome have a characteristic appearance with a narrow bitemporal diameter, almond-shaped eyes with an anti-mongoloid slant, and small hands and feet. They typically have marked hypotonia as infants with subsequent moderate developmental delay and slow somatic growth. Hypothalamic obesity develops during childhood. Patients with congenital adrenal hypoplasia resulting from mutations in the DAX1 transcription factor also have defective development of the ventromedial hypothalamus and consequent hypogonadotrophic hypogonadism, 146 Chapter 4: Reproductive Disorders

associated with adrenal insufficiency that typically presents with aldosterone deficiency and salt wasting. . Constitutional delay is very important functional cause of pubertal delay. . Systemic causes such as chronic illness, malnutrition, excessive exercise, and stress also result in low gonadotrophin concentrations. They cause a temporary delay or a slow progress of puberty. Constitutional Delay of Growth and Puberty (CDGP) It is a variation of normal development that can be difficult to differentiate from pathological hypogonadotrophic hypogonadism. In this condition, puberty and the pubertal growth spurt occur at or later than the extreme upper end of the normal age. The diagnosis is made more often in boys than girls, likely due to referral bias, and has a strongly familial pattern. Skeletal maturation is delayed in comparison with chronologic age. CDGP results in delayed but normal puberty; thus puberty progresses through the normal stages but starts at a later time. Children with CDGP achieve their genetic potential for height, and laboratory evaluation is normal. Some patients benefit from short-term treatment to augment secondary sexual development and boost linear growth. . The vast majority of children presenting with pubertal delay have just a functional delay. . Some boys have abnormalities of psychosocial adjustment and may benefit from treatment. In many cases, the main source of psychosocial concern is short stature rather than the delay in puberty. In these patients, treatment with a short course of depot testosterone to induce puberty may be considered. Once activated, puberty progresses spontaneously despite withdrawal of treatment. . Girls, usually do not require any treatment apart from serial monitoring. However, if required, in those with psychosocial concerns, a short course of estradiol therapy may be offered. They are then allowed to progress spontaneously after discontinuation of treatment. . Treatment of the underlying cause may resolve the pubertal delay, with subsequent spontaneous pubertal progression. In those with a severe delay, treatment may be instituted with a short course of sex steroids until spontaneous pubertal development recovers. Blueprint in Pediatric Endocrinology 147

Hypothalamic-Pituitary Disorders Congenital gonadotrophin deficiency can be isolated or be associated with combined pituitary hormone deficiencies. It can also be associated with other systemic features such as anosmia in Kallman's syndrome, midline brain disorders in septo-optic dysplasia and holoprosencephaly, adrenal hypoplasia, or with other syndromes such as Prader-Willi, Bardet-Biedl, and CHARGE syndromes. Several genes have been linked to the pathogenesis of congenital gonadotrophin deficiency, including KAL1, FGFR1, GPR54, Kiss-1, GnRHR, PROK2, PROKR2, NELF, DAX1, Leptin, Leptin receptor, and prohormone convertase 1 (PC1) genes. Acquired forms of gonadotrophin deficiency are associated with intracranial trauma, tumors, surgery, or radiotherapy. Histiocytosis, sickle cell disease, and iron overload (associated with transfusion) can result in permanent gonadotrophin deficiency. Hypergonadotrophic Hypogonadism Girls . X chromosome abnormalities o Gonadal dysgenesis o Tuner syndrome (45,X) o Swyer syndrome (46,XY) o Mixed gonadal dysgenesis (46,XX/46,XY) o Pure ovarian agenesis (46,XX) . Fragile X permutation . Galactosemia . Blepharophimosis ptosis epicanthus inversus syndrome . -subunit gene mutation . FSH or LH receptor gene mutations Boys . Klinefelter syndrome . Anorchia . LH receptor gene mutation . Acquired o Anorchia 148 Chapter 4: Reproductive Disorders

o Toxins o Radiation o Chemotherapy . Trauma/surgery . Inflammation o Infections . Autoimmunity Gonadal Disorders . Congenital disorders include cryptorchidism / anorchia. . Chromosomal disorders include Klinefelter's syndrome (XXY), Turner's syndrome (45XO), XY gonadal dysgenesis, and 45X / 46XY mixed gonadal dysgenesis. . Acquired causes include testicular torsion, polyglandular autoimmune diseases, chemotherapy, viral infections (such as mumps), pelvic or abdominal radiation, and testicular or ovarian surgery. Turner's syndrome Patients with Turner's syndrome have normal female external genitalia and a normal uterus and fallopian tubes, but they have dysgenetic streak ovaries. Most fetuses with Turner's syndrome spontaneously abort, but the incidence in live births is approximately 1 in 2500. Classically, the karyotype is 45, XO, but many patients retain an abnormal second X chromosome or even a fragment of a Y chromosome lacking SRY. Other patients are mosaic for 46, XX and 45, XO cells and may have relatively mild phenotypes. Untreated patients are short. Many have typical dysmorphic features including lymphedema of the neck at birth, webbed neck, low posterior hairline, increased carrying angle of the arms, and shield chest with widely spaced nipples, low-set ears, and micrognathia. Patients typically have primary amenorrhea and are infertile, but occasionally they can have menarche followed by premature ovarian failure. Blueprint in Pediatric Endocrinology 149

Fig. (4-5): Showed Clinical Features of Turner’s syndrome. Klinefelter's Syndrome

In this condition, male patients have normal development of the penis and scrotum, but the testes are small and firm. Patients tend to be tall. At adolescence, gynaecomastia is frequent. Signs of testosterone deficiency occur in most affected adults, and most have azoospermia. The usual karyotype is 47, XXY. Hormonal findings include elevated gonadotropin levels and decreased serum testosterone concentration. Klinefelter's syndrome is a common disorder that occurs in 1 in 500 to 1000 men. 150 Chapter 4: Reproductive Disorders

Fig. (4-6): Showed Clinical Features of Klinefelter's Syndrome. Investigations of delayed puberty Initial investigations should include a bone age helps to predict the estimated adult height range and its relation to the mid-parental height. The most commonly used method is that of Greulich and Pyle. Measurement of serum FSH and LH concentrations will help to differentiate patients with hypogonadotrophic hypogonadism (low levels) and hypergonadotrophic hypogonadism (elevated levels). The measurements should be performed on an early-morning blood sample using an ultrasensitive pediatric assay. As the hypothalamic-pituitary- gonadal axis is quiescent up to about 10 to 12 years of age, levels of these hormones in children less than 12 years of age must be interpreted with caution. It may occasionally be difficult to distinguish constitutional delay from organic gonadotrophin deficiency, as the basal gonadotrophin concentrations may be low in both groups. Gonadotrophin-releasing hormone (GnRH) stimulation testing should be considered in all patients with low basal gonadotrophin. Girls with Turner's syndrome, and other patients with gonadal abnormalities, typically have marked elevations in basal serum FSH and LH concentrations (in Turner's syndrome from 8 to Blueprint in Pediatric Endocrinology 151

9 years of age), and the GnRH test is most often not indicated in these patients. Human chorionic gonadotrophin (hCG) stimulation test is used to stimulate testicular production of testosterone, and has been suggested to be useful in some patients when combined with the GnRH test to help distinguish constitutional delay from hypogonadotrophic hypogonadism. A rise in serum testosterone concentration is observed in constitutional delay; a decreased testosterone response is seen with hypogonadotrophic hypogonadism. Chromosomal analysis may reveal Klinefelter's syndrome (47XXY) in boys or Turner's syndrome (45XO) in girls. The diagnosis of Turner's syndrome (45XO) should be considered in all short girls. Depending on the mosaicism, 45XO/46XY mixed gonadal dysgenesis may present with ambiguous genitalia at birth or with delayed puberty in adolescence. Pelvic ultrasound examination should be considered in girls with Turner's syndrome or other forms of gonadal dysgenesis. It may reveal dysgenetic gonads. Abdominal ultrasound may reveal renal abnormalities such as agenesis or a horseshoe kidney. Echocardiography in girls with Turner's syndrome may show cardiac defects, including coarctation of the aorta and a bicuspid aortic valve. Neuroimaging of the brain helps to identify structural hypothalamic- pituitary abnormalities, midline brain defects, olfactory hypoplasia, and pituitary tumors. Other pituitary hormone tests to rule out combined pituitary deficiencies should be considered in patients with confirmed hypogonadotrophic hypogonadism, measurement of serum ovarian antibodies to identify an autoimmune process. Thyroid function tests and serum prolactin concentrations are useful in identifying patients with hypothyroidism or hyperprolactinaemia, both of which can present with delayed puberty. Treatmen of delayed puberty The main aims of treatment are ensuring attainment of secondary sexual characteristics and induction of the pubertal growth spurt. Most patients have temporary delay of puberty, particularly boys who have constitutional delay in puberty, and are best observed with serial monitoring. If a specific underlying disorder causing pubertal delay is identified, such as a chronic illness, stress, malnutrition, or excessive 152 Chapter 4: Reproductive Disorders

exercise, it must be treated. Patients with a pituitary tumor need urgent evaluation and a neurosurgical review. Surgery is indicated in most instances. Hormonal therapy is reserved for patients with hypogonadotrophic hypogonadism), for those with a gonadal abnormality (e.g., Turner's syndrome, Klinefelter's syndrome), and for those with constitutional delay who have abnormal psychosocial adjustment. Typically, those with constitutional delay require a short course to activate puberty. In boys Testosterone 50 mg intramuscular injection monthly for 3-6 months, while girls a low dose of conjugated estradiol of 0.3 mg daily for 6 months will stimulate starting of puberty in order to relieve the psychosocial adjustment with peers. Patients with an organic (permanent) cause need lifelong sex-steroid replacement. Pubertal induction and lifelong hormone replacement is almost certainly required in patients with congenital gonadotrophin deficiency and males with anorchia, Patients with acquired gonadotrophin deficiency (following radiation, pituitary surgery, trauma, or iron overload); those with congenital gonadal abnormalities such as cryptorchidism, Klinefelter 's syndrome, Turner's syndrome, and other forms of gonadal dysgenesis (e.g., XY gonadal dysgenesis, 45XO/46XY mixed gonadal dysgenesis); and those with acquired gonadal abnormalities such as testicular damage following torsion or surgery, autoimmune disorders, chemotherapy, or viral infections (e.g., mumps in males). Re-testing at the end of growth and puberty to ascertain the need for long-term replacement may be indicated in some of those patients who had ambiguous results pre-puberty. Pubertal Induction In males, pubertal induction is carried out gradually, with increasing doses of intramuscular testosterone therapy until adult levels are reached. Doses are typically increased gradually over approximately 2 years, at 6- month intervals. Some boys report symptoms of irritability, aggression, and hypersexuality in the days following the injection. In females require gradually increasing doses of estrogen treatment, with cyclic progesterone therapy introduced when adequate estrogenisation has occurred or at the onset of uterine breakthrough bleeding. Blueprint in Pediatric Endocrinology 153

Puberty should not be induced using contraceptive pills or patches because the doses of estrogen are too high and the androgenic progestogen impairs optimal breast development. The dose is increased gradually over approximately 2 years, at 6-month intervals, to a full adult dose and/or until breast development is satisfactory. . Delayed puberty is defined as the lack of any pubertal signs by the age of 13 years in girls and 14 years in boys. . It is more common in boys. . May be functional (constitutional delay, underlying chronic disease, malnutrition, excessive exercise) or organic, due to either a lack of serum gonadotrophin production or action (hypogonadotrophic hypogonadism), or gonadal insufficiency with elevated gonadotrophin (hypergonadotrophic hypogonadism). . Most patients seek medical assistance because of slow growth rather than slow pubertal development. . Careful assessment of height and pubertal stage is crucial for evaluation of the underlying cause. . The distinction between organic gonadotrophin deficiency and constitutional delay of puberty is not easy and is often resolved only with time. . Sex-steroid treatment is reserved for those with psychosocial worries, and consists of a short course of sex steroids to induce puberty. . Patients with an organic cause for delay are given sex-steroid therapy to induce puberty and require lifelong hormone replacement therapy after puberty is complete. Polycystic Ovarian Syndrome (PCOS) In 1935, Stein and Leventhal first described this syndrome. Key features include hyperandrogenism, menstrual dysfunction, and exclusion of other causes of hyperandrogenism (e.g, congenital adrenal hyperplasia, androgen-secreting tumors, and hyperprolactinaemia). Probable criteria included insulin resistance, elevated luteinizing hormone to follicle stimulating hormone ratio, and polycystic ovaries identified using ultrasonography. 154 Chapter 4: Reproductive Disorders

Fig. (4-7): Showed Polycystic Ovaries Seen in Ultrasound Study. The hyperandrogenic effects observed in polycystic ovarian syndrome most commonly include hirsutism, acne, or androgen- dependent alopecia. Obesity is also common. Endocrine abnormalities include elevated serum concentrations of androgens (particularly testosterone and androstenedione), increased LH levels, and normal or decreased FSH levels. Polycystic ovarian syndrome is also associated with insulin resistance and changes in lipid metabolism. . A common mnemonic acronym for the clinical association of hyperandrogenism, insulin resistance, and acanthosis nigricans is the HAIRAN syndrome. Androgens such as testosterone, and dehydroepiandrosterone sulfate (DHEAS) may or may not be elevated in the peripheral circulation. The source of androgens may be from the ovaries, adrenals, or both. Other contributing factors to androgen excess include an elevated serum level of androstenedione (which is converted within adipose tissue to testosterone) and a greater percentage of unbound active testosterone circulating in the peripheral blood. Approximately 40% of patients with polycystic ovarian syndrome have insulin resistance that is independent of body weight and are at increased risk for type 2 diabetes mellitus with consequent cardiovascular complications. Key Points . Irregular menses during the first two years after menarche are most often physiologic, requiring no special evaluation. Blueprint in Pediatric Endocrinology 155

. Persistent clinical symptoms beyond this time, especially in the presence of other signs of polycystic ovarian syndrome, warrant further evaluation. . Adolescent females with PCOS may present with amenorrhea, oligomenorrhea, dysfunctional uterine bleeding, or infertility. Menarche may be delayed, and primary amenorrhea, although uncommon, does occur. . Hyperandrogenism presents as hirsutism, acne, and male pattern alopecia. . Other signs of hyperandrogenism (clitoromegaly, increased muscle mass, voice deepening) are more characteristic of an extreme form of polycystic ovarian syndrome termed hyperthecosis. . These signs and symptoms could also be consistent with androgen-producing tumors, exogenous androgen administration, or virilizing congenital adrenal hyperplasia. . Acanthosis nigricans which is a dark and thickened area of skin behind the neck and in skin folds also is a common clinical feature. . Obesity, although common but is not universal. Obesity is not usually the presenting complaint. . Polycystic ovarian syndrome is, in some cases, a familial disorder; some of cases have an evidence of an autosomal dominant mode of inheritance.

Laboratory Studies The goal in patients with polycystic ovarian syndrome (PCOS) is to assess the severity and source of androgen excess and to rule out an adrenal or ovarian tumor. Karyotype usually excludes mosaic Turner syndrome as a cause of the primary amenorrhea.FSH levels are within the reference range or low. LH levels are elevated for Tanner stage, gender, and age. The LH: FSH ratio is usually more than 1. A small percentage of patients have elevated prolactin levels. Thyroid function tests are within the reference range in patients with polycystic ovarian syndrome.Free testosterone levels are sensitive for ovarian hyperandrogenism and are elevated in patients with polycystic ovarian syndrome. Sex hormone-binding globulin (SHBG) is concomitantly low. 156 Chapter 4: Reproductive Disorders

DHEAS is a marker of adrenal androgen production which is high. Androstenedione levels are also elevated. Some females with polycystic ovarian syndrome have insulin resistance and an abnormal lipid profile (cholesterol >200 mg/dl; LDL >160 mg/dl). Approximately one third of them is overweight and has impaired glucose tolerance or type 2 diabetes mellitus by age 30 years. Pelvic ultrasound the criteria for polycystic ovaries include bilateral ovarian enlargement (> 9 cm in diameter), 10 or more follicles 2-10 mm in diameter per ovary, and increased density of the stroma. Treatment First-line medical therapy usually consists of changing life style with weight reduction, oral contraceptive to suppress ovarian androgen production and induce regular menses. If symptoms such as hirsutism are not sufficiently alleviated, an androgen-blocking agent may be added e.g. Finasteride, which is 5 α- reductase enzyme inhibitor, dose of 5 mg once daily. Flutamide is a potent antiandrogen with rare risk of hepatotoxicity and expense. Cyproterone acetate is a progestin with anti androgenic activity with dose of 50 – 100 mg daily or it is added with low dose with oral contraceptive "Diane". Spirinolactone is the safest and potent antiandrogen to be used with dose of 100 mg twice daily for first 9-12 months, then dose to be reduced into 50 mg orally twice daily as maintainance therapy. If the patient has failed to suppress adrenal hyperandrogenism, then treatment with low dose prednisone or dexamethasone may be considered. Several medications, including benzoyl peroxide, Retin-A, and topical and oral antibiotics, are effective for acne treatment. If the patient has insulin resistance or developed type 2 diabetes mellitus, consider treatment with oral insulin sensitizer, such as Metformin, starting dose of 500 mg daily with building up the dose gradually of maximum 2000 gram /day. Clinical trials have recently shown that Metformin can effectively reduce androgens, improve insulin sensitivity, and facilitate weight loss in patients with polycystic ovarian syndrome as early as adolescence. The patient may desire mechanical removal of excess hair. Options include electrolysis, waxing, bleaching, tweezing, depilatories, shaving, and laser removal. Clomiphene citrate is used to stimulate ovulation when fertility Blueprint in Pediatric Endocrinology 157

is desired. Other approaches use gonadotropin-releasing hormone (GnRH) analogues to suppress LH secretions with subsequent decrease androgen synthesis. Ovarian wedge resection was formerly considered an effective treatment for polycystic ovarian syndrome. Since the advent of hormonal therapies, this treatment is not often used but may be effective in alleviating ovarian dysfunction. Laparoscopic "ovarian drilling" is now performed. Hirsutism Normally, there are two types of hair, vellus hairs, which are fine, unpigmented that cover most of the body before puberty. Pubertal androgens promote the conversion of these vellus hairs to coarser, pigmented terminal hairs. The level and duration of exposure to androgens, the local 5-á-reductase activity, and the intrinsic sensitivity of the hair follicle to androgen action determine the extent of conversion from vellus to terminal hair. Dihydrotestosterone is the androgen that acts on the hair follicle to produce terminal hair. The local production of dihydrotestosterone is determined by 5-á-reductase activity in the skin. Differences in the activity of this enzyme may explain why women with the same plasma levels of testosterone can have different degrees of hirsutism. Most forms of hirsutism become evident around puberty. This includes polycystic ovary syndrome (PCOS), congenital adrenal hyperplasia, and idiopathic hirsutism. The etiologic forms of hirsutism include endocrine-related, idiopathic, medication-related, and miscellaneous. PCOS is the most common ovarian disorder associated with hirsutism. By definition, polycystic ovaries have 20 or more subcapsular follicles, which range from approximately 1-15 mm in diameter. The follicles are at various states of atresia, and hyperplasia of the theca interna, the anatomic source of ovarian androgens, is present. Adrenal tumors: are almost always malignant in patients who present with hirsutism. These tumors are usually large and are associated with a very poor prognosis. Cushing syndrome caused by glucocorticoid therapy. Glucocorticoid therapy is one of the causes of hypertrichosis, resulting in vellus hair growth, especially on the face. CAH is actually a family of defects in 1 of 5 enzymes that are responsible for the 158 Chapter 4: Reproductive Disorders

biosynthesis of cortisol, only 3 of these enzyme deficiencies produce hirsutism which are 21-hydroxylase (most frequent deficient enzyme), 3- β -hydroxysteroid dehydrogenase (less frequent), and 11-β -hydroxylase deficiency (least frequent). Ovarian tumors may be malignant, and the threat can be serious. Androgen-secreting ovarian tumors are a less- serious threat. The most common among them is arrhenoblastoma, which accounts for less than 1% of all ovarian tumors. In patients with this neoplasm, the serum testosterone level is always elevated, and most patients have amenorrhea and a palpable ovarian mass. Idiopathic hirsutism is a diagnosis of exclusion. The spectrum of clinical presentations ranges from normal menses and mild hirsutism to amenorrhea and signs of virilization, and testosterone levels range from normal to frankly elevated. The hirsutism usually begins at puberty. The disorder is often familial and may be associated with obesity and insulin resistance. Some patients with idiopathic hirsutism have normal plasma androgen levels, the underlying mechanism in these patients may be an increase in androgen sensitivity or in 5-α-reductase activity in the skin. Ferriman-Gallwey Score for Hirsutism

Fig. (4-8): Showed Ferriman-Gallwey Score for Hirsutism.

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The scoring system quantifies the extent of hair growth in nine key anatomical sites. Hair growth is graded using a scale from zero (no terminal hair) to 4 (maximal growth), for a maximum score of 36. A score of 8 or more indicates the presence of androgen excess. The degree of facial and body hair excess can be objectively scored by this method. Key points . Hypertrichosis should not be confused with hirsutism because hirsutism usually implies hyperandrogenism. . Hypertrichosis usually involves nonandrogenic hair. . Hypertrichosis can be caused by porphyria, medications (phenytoin, minoxidil, cyclosporine, diazoxide, corticosteroids, streptomycin, penicillamine, heavy metals, acetazolamide, interferon), and genetic factors.

Laboratory Studies

The most important assay is the level of serum testosterone, the major circulating androgen. If the total serum testosterone level is normal, measure the free serum level because hyperandrogenism (and insulin resistance, if present) decreases sex steroid-binding globulin, such that the unbound, biologically active testosterone moiety may be elevated even if the total level is unremarkable. Measurement of elevated plasma levels of DHEAS, an androgen synthesized almost exclusively by the adrenal cortex, can indicate excess adrenal function. Elevations in both testosterone and DHEAS suggest an adrenal origin, whereas an isolated testosterone elevation indicates an ovarian source. Dexamethasone suppression diagnostic trial therapy for 7-14 days can be initiated to help exclude (ACTH)–dependent hirsutism. Then to repeat, free testosterone, DHEAS, and plasma cortisol levels. Dexamethasone-mediated suppression of androgens is observed in those with congenital adrenal hyperplasia and idiopathic hirsutism. In adolescents with PCOS or adrenal / ovarian tumors are associated with normal suppression of cortisol by dexamethasone, whereas cortisol levels in patients with Cushing syndrome are not suppressed. Serum 17-hydroxyprogesterone levels obtained between 07:00 and 09:00 hours. Values less than 7 nmol/l exclude the diagnosis, and values of 160 Chapter 4: Reproductive Disorders

greater than 45 nmol/l confirm 21-hydroxylase deficiency. When basal values of 17-hydroxyprogesterone are between 7 and 45 nmol/l, an ACTH-stimulated concentration of greater than 45 nmol/l is also diagnostic. Serum prolactin or FSH in adolescents with hirsutism and amenorrhea of unknown cause should have a serum prolactin and FSH test to evaluate for either a prolactinoma or ovarian failure. Diabetes screening in adolescents with hirsutism, PCOS, obesity, or acanthosis nigricans may have insulin resistance, and screening for diabetes and hyperlipidemia. Imaging Studies If indicated based on the findings from the clinical evaluation and laboratory testing, perform ovarian ultrasonography and adrenal computed tomography scanning or magnetic resonance imaging to evaluate for either ovarian or adrenal sources of androgen production. Treatment The systemic therapies include glucocorticoid, oral contraceptives, spironolactone, flutamide, finasteride, Cyproterone acetate, and insulin sensitizers (Metformin). Doses previously mentioned in PCOS section. Glucocorticoid (dexamethasone or prednisone) in congenital adrenal hyperplasia or idiopathic adrenal hyperandrogenism. Usually, 0.25-0.5 mg of dexamethasone at bedtime is sufficient to suppress ACTH and adrenal androgen production. Unfortunately, some patients gain weight and develop Cushingoid features, even with this small of a dose. Oral contraceptive therapy is probably the first choice for hirsutism. They are inexpensive and promote regular uterine bleeding. In addition, they can be used in combination with one of the antiandrogen or other forms of therapy. It has to be noted that, they should not be used in adolescents with migraine or those with thromboembolic diseases. Spironolactone, in daily doses of 50-200 mg / day, blocks androgen receptors. Spironolactone also decreases testosterone production, making it additionally effective for hirsutism. Six months to a year of therapy is usually required before results are noticeable response. Even then, only approximately one half to three quarters of patients shows improvement. Blueprint in Pediatric Endocrinology 161

. The nature of the hair follicle, which persists for six months to a year even after androgen levels have been normalized.

Finasteride is a 5-α-reductase inhibitor approved for the treatment of hirsutism and the efficacy is similar to that of spironolactone. Finasteride could be added to spironolactone, demonstrating an additive reduction in hirsutism scores. The main concern with finasteride is the risk of ambiguous genitalia in male fetuses exposed to the enzyme inhibitor during the first trimester. Therefore, use this drug only in females with no desire of becoming pregnant. Flutamide is a potent non steroidal selective antiandrogen without progestational, estrogenic, corticoid, or anti-gonadotropin activity. Preliminary data indicate that it is effective as therapy for hirsutism and acne; however, flutamide is expensive and has caused fatal hepatitis. Cyproterone acetate has been effective in the treatment of hirsutism. When added to ethinyl estradiol, it is as effective as flutamide in the treatment of hirsutism. Metformin improve insulin resistance and have been shown to be effective in lowering androgen levels and in treating hirsutism. Cosmetic measures for hirsutism are hydrogen peroxide bleaching, plucking, waxing, shaving, chemical depilatories, electrolysis and laser therapy. Gynecomastia Gynaecomastia is the benign enlargement of the male breast with firm tissue extending concentrically beyond the nipple. Histologically gynaecomastia is benign proliferation of breast ducts and duct epithelial hyperplasia accompanied by varying amounts of inflammation, edema, stroma, and fibrosis. If male breast enlargement was entirely due to adipose tissue, it is called pseudo-gynaecomastia. Estrogen stimulates breast duct development in both males and females in the presence of permissive levels of GH, FSH, and LH from the pituitary. Progesterone stimulates development of breast alveoli. Androgens oppose estrogen action. Prolactin is not a growth factor for the breast in men, but prolactin suppresses the hypothalamic generator of GnRH pulses that stimulate production of LH and FSH. Gynaecomastia results from a relative excess of estrogen or estrogen action or a relative deficiency of androgen or androgen action. Testosterone is converted to 162 Chapter 4: Reproductive Disorders

estrogen by the enzyme aromatase, which also converts androstenedione to the weak estrogen (estrone). Aromatase is found predominately in adipose tissue. In the blood, 50% to 60% of testosterone is tightly bound to sex hormone binding globulin. Most of the rest is weakly bound to albumin and is considered bio-available. Only the small free testosterone fraction (0.5% to 3%) is active. Free testosterone declines slowly with age. Estrogen is less strongly bound to sex hormone binding globulin than testosterone. Defects in any of these pathways can cause gynaecomastia.

Fig. (4-9): Showed pubertal bilateral gynecpmastia in 13- Year-Old boy. Estrogen excess or increased estrogen sensitivity stimulates proliferation of breast ducts and ductal epithelium. If androgen deficiency or androgen inhibition is present, the effect of estrogen is more pronounced, even if the estrogen level is normal. At puberty, marked increases in GH, insulin-like growth factor 1, and LH drive both estrogen and testosterone production, but the estrogen peak precedes the peak in testosterone production. Neonatal Gynaecomastia A physiological response to high levels of maternal and placental estrogen transferred in-utero. A secretion sometimes called witch's milk often can be expressed. Is considered physiological and does not require assessment or intervention. Blueprint in Pediatric Endocrinology 163

Fig. (4-10): Shwing unilateral neonatal gynecomastia. Pubertal Gynaecomastia Is relatively common condition that results from imbalance between estrogens and androgens.A physiological response to the increase in testosterone fuelled by marked increases in GH, insulin-like growth factor-1, FSH, and LH at puberty. Estrogen increases three folds, but peaks earlier than testosterone. Heriditary Gynecomastia Recently described condition, where there is an overexpression of Aromatase gene CYP19A1 and resultant of estrogen excess. This condition was labeled as aromatase excess syndrome (AEXS). AEXS is rare autosomal dominant disorder; overexpression gene is located at choromosome 15q21. This disorder is characterized with pre or peri pubertal gynecomastia, mild hypogonadotrophic hypogonadism in males, advanced bone age, mild to moderate short adults. Male patients usually have normal-looking genetalia at birth and usually normal fertility. Female patients with AEXS usually are not symptomatic, although multiple clinical features such as macromastia, precocious puberty and short stature have been described in some patients. 164 Chapter 4: Reproductive Disorders

Causes of Elevated Estrogen Levels or Activity . Excess aromatase activity seen in obesity, congenital activating mutation of aromatase, tumors (Sertoli cell, Leydig cell, germ cell). . Excess androgen converted to estrogen in testicular feminization, anabolic steroid use, excessive androgen replacement therapy, cirrhosis. . Chronic illness or starvation and re-feeding will have more profound suppression of testosterone than estrogen with fasting, and earlier increase in estrogen than testosterone with re-feeding. . Estrogen-producing tumors for example, sertoli cell, leydig cell, germ cell, hCG producing tumors (stimulate Leydig cell estrogen production), feminizing adrenal adenocarcinoma. . Exogenous estrogen exposure like accidental ingestion of contraceptive pills. . Drugs that stimulate estrogen receptors e.g. diethylstilbestrol, digitalis and phenytoin. . Hyperthyroidism. . Recently described Aromatase excess syndrome (AEXS). Causes of Testosterone Deficiency . Hypogonadotropic hypogonadism (Kallman's syndrome). . Hyperprolactinaemia seen in pituitary tumor, hypothyroidism, renal disease (GnRH pulse generator suppression). . Testicular causes such as, castration, infection (orchitis), infiltration (haemochromatosis), chemotherapy- or radiation-related damage to leydig cells, neurological diseases (spinal cord injury, myotonic dystrophy), Klinefelter syndrome (47 XXY). . Medications: GnRH agonists, cancer chemotherapeutic agents, ketoconazole, metronidazole, spironolactone, some antipsychotic agents. Causes of Impaired Testosterone Action . Elevated estrogen levels. . Genetic factors. Blueprint in Pediatric Endocrinology 165

. Medications, such as anticonvulsants, androgen receptor blockers (bicalutamide, flutamide), spironolactone, 5-α- reductase inhibitors, H2 receptor blockers (cimetidine more than ranitidine), and proton pump inhibitors (impair testosterone action less than H2 blockers). Diagnosis After verifing that the breast enlagment is due to a true glandular enlargment, we assess; neonatal onset and size less 4 cm, then only pedagtric follow up is required. If there is breast tenderness and size is more than 4cm with absence of causative agent, then serum testosterone, LH, FSH, and hCG should be measured. Based on the results one should evaluate the following; androgen deficincy sndrome, tumors, and increased aromatization of androgens to estrogen. Treatment Pubertal Gynaecomastia Gynaecomastia usually resolves spontaneously. Boys at puberty with normal sexual development need reassurance that gynaecomastia is normal and that the condition usually resolves within 6 to 24 months. The selective estrogen receptor modulators (SERMs) tamoxifen and raloxifen have shown comparable effectiveness in a small study of pubertal boys with persistent gynaecomastia of duration more than 2 years. SERMs are preferred therapy where needed. Androgens are less preferred to SERMs, despite the fact that testosterone reduced breast diameter in small groups of pubertal boys. But usually used in cases secondary to hypogonadism. Aromatase inhibitors for example (anastrazole or Letrazole) usually not effective therapy in most cases of gynecomastia apart from if gynecomastia is secondary to AEXS, where is effective tool, although long term safety of anastrazole therapy still to be assessed. Surgical treatment is not generally recommended in pubertal and adolescent groups. Where it is indicated, in cases with persistent pain and extensive tissue deposition causing significant embarrassment, it is usually deferred until the testicles are adult size (or 2 years after initial findings of gynaecomastia) and puberty is nearing completion. This allows the testosterone/estrogen ratio to reach adult proportions. Direct surgical excision is needed for more extensive or redundant tissue. Combined surgery may also be appropriate. Liposuction (with or without ultrasound) is used for removal of adipose tissue with a small glandular 166 Chapter 4: Reproductive Disorders

component. Usually, it is not advisable because of pain and high recurrence rate. Further Reading 1. Carr, B.R. (1998) Disorders of the ovaries and female reproductive tract. In: Williams Textbook of Endocrinology (eds J.D. Wilson, D.W. Foster, H.M. Kronenberg & P.R. Larsen), 9th edn, pp. 751– 818. W.B. Saunders. 2. Griffen, J.E. & Wilson, J.D. (1998) Disorders of the testes and male reproductive tract. In: Williams Textbook of Endocrinology (eds J.D. Wilson, D.W. Foster, H.M. Kronenberg & P.R. Larsen), 9th edn, pp. 819–876. W.B. Saunders. 3. Kelly, B.P., Paterson, W.F., Donaldson, M.D.C. (2003). Final height outcome and value of height prediction in boys with constitutional delay in growth and adolescence treated with intramuscular testosterone 125mg per month for 3 months. Clinical Endocrinology 58: 267–272. 4. Marshall, W.A. & Tanner, J.M. (1969) Variations in pattern of pubertal changes in girls. Archives of Disease in Childhood 44,291–303. 5. Marshall, W.A. & Tanner, J.M. (1970) Variations in the pattern of pubertal changes in boys. Archives of Disease in Childhood 45, 13–23. 6. Paterson, W.F., Hollman, A.S., McNeill, E. & Donaldson, M.D.C. (1998) Use of long acting goserelin in the treatment of girls with precocious and early puberty. Archives of Disease in Childhood 79, 323–327. 7. Tanner, J.M. (1962) Growth at Adolescence, 2nd edn, Blackwell, Oxford. Tsilchorozidou, T., Overton, C. & Conway, G.S. (2004). The pathophysiology of polycystic ovarian disease. Clinical Endocrinology 60 (1):1–17. 8. Fukami M, Shozu M, Ogata T. Molecular Bases and Phenotypic Determinants of Aromatase Excess Syndrome. Int J Endocrinol 2012; 584807.

Chapter 5

Thyroid Disorders in Children

. Introduction . The Thyroid Gland . The Placenta and the Thyroid Gland . Physiology the Thyroid Gland . Thyroid hormone synthesis . Congenital Hypothyroidism (CH) o Causes of permanent congenital hypothyroidism o Thyroid dysgenesis o Dyshormonogenesis . Secondary and /or tertiary Hypothyroidism . Transient neonatal hypothyroidism . Maternal antithyroid medication . Maternal thyrotropin receptor antibodies . Maternal hyperthyroidism . Prematurity . Clinical manifestations of congenital hypothyroidism . Diagnosis of congenital hypothyroidism . Treatment of of congenital hypothyroidism . Prognosis of of congenital hypothyroidism . Causes of hypothyroidism in childhood and adolescence . Thyroiditis . Acute suppurative thyroiditis . Subacute thyroiditis (de Quervain disease) . Hashimoto‘s thyroiditis "Chronic Lymphocytic thyroiditis (CLT)" . Diagnostic tests in thyroiditis . Investigation of thyroiditis . Treatment of thyroiditis . Drugs of goitrogens . Secondary or tertiary hypothyroidism . Clinical manifestations of acquired hypothyroidism . Diagnosis and treatement of acquired hypothyroidism

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. Average daily doses of L-Thyroxin . Hyperthyroidism . Transient neonatal hyperthyroidism . Clinical manifestations of hyperthyroidism . Neonatal thyrotoxicosis . Permanent neonatal hyperthyroidism . Causes of Hyperthyroidism inchildhood and adolescence . Graves‘ disease o Clinical manifestations o Diagnosis o Treatment . Medical therapy . Radioactive Iodine . Surgery . Causes of goitre . Resistance to Thyroid Hormone (RTH) o Clinical features o Diagnosis o Treatment of children with RTH o Future of RTH therapy

Introduction The thyroid gland is a butterfly-shaped and is composed of two lobes, connected via the isthmus. It is situated on the anterior side of the neck, lying against and around the larynx and trachea, reaching posteriorly the esophagus and carotid sheath. The thyroid is one of the larger endocrine glands, weighing 2-3 grams in neonates and 18-60 grams in adults, and is increased in pregnancy. In the fetus, at 3–4 weeks of gestation, the thyroid gland appears as an epithelial proliferation in the floor of the pharynx at the base of the tongue. The thyroid then descends in front of the pharyngeal gut as a bilobed diverticulum through the thyroglossal duct. Over the next few weeks, it migrates to the base of the neck, passing anterior to the hyoid bone. During migration, the thyroid remains connected to the tongue by a narrow canal, the thyroglossal duct.

Fig. (5-1): Showed Normal Anatomy of Thyroid Gland. Thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) start being secreted from the fetal hypothalamus and pituitary at 18-20 weeks of gestation, and fetal production of thyroxin (T4) reach a clinically significant level at 18–20 weeks. Fetal self- sufficiency of thyroid hormones protects the fetus against e.g. brain development abnormalities caused by maternal hypothyroidism. However, preterm births can suffer neurodevelopment disorders due to

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lack of maternal thyroid hormones due their own thyroid being insufficiently developed to meet their postnatal needs. The parafollicular C cells, those responsible for the production of calcitonin, are derived from the neural crest. The Placenta and The Thyroid Gland In the human infant under normal circumstances, the placenta has only limited permeability to thyroid hormone and the fetal hypothalamic- pituitary- thyroid system develops relatively independent of maternal influence. There is also evidence that maternal-fetal T4 transfer occurs in the first half of pregnancy, when fetal thyroid hormone levels are low. It seems likely that when fetal thyroid function is normal, the net flux of T4 from mother to fetus is relatively limited. However, when the fetus is hypothyroxinemic, there is significant bulk transfer of T4 to the fetal circulation. The Full-Term Neonate Marked changes occur in thyroid physiology at the time of birth in the full term newborn. One of the most dramatic changes is an abrupt rise in the serum TSH which occurs within 30 minutes of delivery. Peak TSH concentrations in the full term infant can reach up to 60 to 70 mU/l at 6 hours of life. This causes a marked stimulation of the thyroid and an increase in the concentrations of both serum T4 and T3. These consist of an approximate 50% increase in the serum T4 and an increase of three- to four-fold in the concentration of serum T3 to adult levels within 24 hours. Serum levels of T4, free T4 and TBG remain elevated over cord levels at 7 days of postnatal life, decreasing thereafter. The T3 concentration rises strikingly at Day 7, and continues to rise for the first 28 days. Premature Infants Thyroid function in the premature infant reflects the relative immaturity of the hypothalamic-pituitary-thyroid axis. Following delivery, there is a surge in T4 and TSH analogous to that observed in term infants, but the magnitude of the increase is less in premature neonates. In infants < 32 weeks, the circulating T4 concentration may not increase and may even fall in the first 1 to 2 weeks of life. This decrease in the T4 concentration is particularly significant in very premature infants, in whom the serum T4 may occasionally be undetectable. In most Blueprint in Pediatric Endocrinology 171

cases, the total T4 is more affected than the free T4, a consequence of abnormal protein binding and /or the decreased TBG in these babies with immature liver function. Physiology The Thyroid Gland

The thyroid hormones, thyroxin (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland primarily responsible for regulation of metabolism. An important component in the synthesis of thyroid hormones is iodine. The major form of thyroid hormone in the blood is thyroxin (T4), which has a longer half-life than T3. The ratio of T4 to T3 released into the blood is roughly 20 to 1. Thyroxin is converted to the active T3 (three to four times more potent than T4). Most of the thyroid hormone circulating in the blood is bound to transport proteins (70% is bound to thyroxin-binding globulin (TBG); 10- 15% is bound to prealbumin. Only a very small fraction of the circulating hormone is free (unbound) and biologically active, hence measuring concentrations of free thyroid hormones is of great diagnostic value. When thyroid hormone is bound, it is not active, so the amount of free T3/T4 is what is important. For this reason, measuring total thyroxin in the blood can be misleading. Free thyroxin is only 0.03 % of total T4and free T3 constitutes 0.3% of total T3. Thyroid hormones are lipophilic substances that are able to traverse cell membranes even in a passive manner. The thyronines act on nearly every cell in the body. They act to increase the basal metabolic rate, affect protein synthesis, help regulate long bone growth (synergy with growth hormone) and neuronal maturation, and increase the body's sensitivity to catecholamine (such as adrenaline) by permissiveness. The thyroid hormones are essential to proper development and differentiation of all cells of the human body. These hormones also regulate protein, fat, and carbohydrate metabolism, affecting how human cells use energetic compounds. They also stimulate vitamin metabolism. Numerous physiological and pathological stimuli influence thyroid hormone synthesis. Thyroid hormone leads to heat generation in humans.

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Thyroid Hormone Synthesis

Thyroid hormones (T4 and T3) are produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotrophs of the anterior pituitary gland. Because the effects of T4 in vivo are mediated via T3 (T4 is converted to T3 in target tissues), T3 is 3- to 5- fold more active than T4.

Fig. (5-2): Showed Histology of Thyroid Gland Follicle. Iodide is actively absorbed from the bloodstream by a process called iodide trapping. In this process, sodium is co-transported with iodide from the baso-lateral side of the membrane into the cell and then concentrated in the thyroid follicles to about thirty times its concentration in the blood. Via a reaction with the enzyme peroxidase, iodine is bound to tyrosine residues in the thyroglobulin molecules, forming monoiodotyrosine (MIT) and diiodotyrosine (DIT). Linking two moieties of DIT produces thyroxin. Combining one particle of MIT and one particle of DIT produces triiodothyronine.

DIT + MIT → rT3 (biologically inactive) MIT + DIT → triiodothyronine (referred as T3) DIT + DIT → thyroxin (referred to as T4)

Proteases digest iodinated Thyroglobulin, releasing the hormones T4 and T3, the biologically active agents central to metabolic regulation. Peripherally, Thyroxin is believed to be a prohormone and a reservoir for the most active and main thyroid hormone T3. T4 is converted as required in the tissues by iodothyronine deiodinase. Deficiency of deiodinase can Blueprint in Pediatric Endocrinology 173

mimic an iodine deficiency. T3 is more active than T4 and is the final form of the hormone, though it is present in less quantity than T4. Congenital Hypothyroidism (CH)

Fig. (5-3): Showed Classical Signs of Congenital Hypothyroidism. It is one of the commonest treatable causes of mental retardation. Although in the initial studies, an incidence of between 1 in 3000 and 1 in 4000 infants worldwide was obtained, the current estimate is even higher (1 in 2,500). Congenital hypothyroidism screening is justified to prevent mental retardation, the diagnosis must be made early, preferably 174 Chapter 5: Thyroid disorders in Children

within the first few days of life; at that age, clinical recognition is difficult if not impossible; sensitive, specific screening tests and simple, cheap effective treatment are available; and the benefit-cost ratio is highly favorable. Since the development of the first screening program of congenital hypothyroidism in Quebec in 1972, newborn screening programs are available in most parts of the world. Newborn infants with congenital hypothyroidism are at risk of permanent mental retardation if thyroid hormone therapy is delayed or inadequate. In contrast, hypothyroidism that develops after the age of three years is characterized predominantly by a deceleration in linear growth and skeletal maturation but there is no permanent effect on cognitive development. In general, infants with severe defects in thyroid gland development or inborn errors of thyroid hormonogenesis present in infancy whereas babies with less severe defects or acquired abnormalities, particularly autoimmune thyroid disease, present later in childhood and adolescence. Causes of Permanent Congenital Hypothyroidism Thyroid Dysgenesis Thyroid dysgenesis may result in the complete absence of thyroid tissue (agenesis) or it may be partial (hypoplasia); or failure to descend into the neck (ectopic). Females are affected twice as often as males. Babies with congenital hypothyroidism have an increased incidence of cardiac anomalies, particularly atrial and ventricular septal defects. An increased prevalence of renal and urinary tract anomalies has also been reported recently. Most cases of thyroid dysgenesis are sporadic. Although both genetic and environmental factors have been implicated in its etiology, in most cases the cause is unknown. Dyshormonogenesis Inborn errors of thyroid hormonogenesis are responsible for most of the remaining cases (15%) of neonatal hypothyroidism. A number of different defects have been characterized and include decreased TSH responsiveness, failure to concentrate iodide, defective organification of iodide due to an abnormality in the peroxidase enzyme or in the H2O2 generating system, defective thyroglobulin synthesis or transport, and abnormal iodotyrosine deiodinase activity. The association of an organification defect with sensorineural deafness is known as Pendred Blueprint in Pediatric Endocrinology 175

syndrome. Though usually included in causes of congenital hypothyroidism because it is caused by a genetic defect, Pendred syndrome rarely presents in the newborn period. . Unlike thyroid dysgenesis, these errors of thyroid hormonogenesis are commonly associated with an autosomal recessive form of inheritance, consistent with a single gene abnormality.

Secondary and/or tertiary Hypothyroidism Central hypothyroidism occurs in 1 in 50,000 to 1 in 100, 000 newborn infants, but, as noted previously, it may be much more common. TSH deficiency may be isolated or it may be associated with other pituitary hormone deficiencies. Familial cases of both TSH deficiency and TRH deficiency have been described. TSH deficiency in association with other pituitary hormone deficiencies may be associated with abnormal midline facial and brain structures (particularly cleft lip and palate, and absent septum pellucidum and/or corpus callosum) and should be suspected in any male infant with microphallus and prolonged hypoglycemia. One of the more common of these syndromes, septo-optic dysplasia, has been related in some cases to a mutation in the HESX1 homeobox gene in some cases. Transient neonatal Hypothyroidism Transient neonatal hypothyroidism should be distinguished from a ‗false positive‘ result in which the screening result is abnormal but the confirmatory serum sample is normal. While iodine deficiency, iodine excess, drugs and maternal TSH receptor blocking antibodies are the most common causes of transient hypothyroidism, in some cases the cause is unknown. Infants, transient hypothyroidism were reported in 20% of premature infants. Premature infants are unusually susceptible to the effects of iodine deficiency not only because of decreased thyroidal iodine stores accumulated in utero, but because of immaturity in both the capacity for thyroid hormonogenesis, the hypothalamic-pituitary-thyroid axis, and in the ability to convert T4 to the more metabolically active T3. Other factors, including increased skin absorption and decreased renal clearance of iodine in premature infants, are also likely to play a role. Reported sources of iodine have included drugs (e.g., potassium iodide, 176 Chapter 5: Thyroid disorders in Children

amiodarone), radiocontrast agents and antiseptic solutions (e.g., povidone-iodine) used for skin cleansing. Maternal Antithyroid Medication Transient neonatal hypothyroidism may develop in babies whose mothers are being treated with antithyroid medication (either propylthiouracil or methimazole) for the treatment of Graves‘ disease. Babies characteristically develop an enlarged thyroid gland and if the dose is sufficiently large, respiratory embarrassment may occur. Both the hypothyroidism and goiter resolve spontaneously with clearance of the drug from the baby‘s circulation. Usually replacement therapy is not required. Maternal Thyrotropin Receptor Antibodies Maternal thyrotropin receptor blocking antibodies, a population of antibodies closely related to the thyrotropin receptor stimulating antibodies in Graves‘ disease, may be transmitted to the fetus in sufficient titer to cause transient neonatal hypothyroidism. Maternal Hyperthyroidism Occasionally, babies born to mothers who were hyperthyroid during pregnancy develop transient hypothalamic-pituitary suppression. This hypothyroxinemia is usually self-limited. Prematurity Hypothyroxinemia in the presence of a ‗normal‘ TSH occurs most commonly in premature infants in whom it is found in 50% of babies of less than 30 weeks gestation. In addition to the hypothalamic-pituitary immaturity, premature infants frequently have TBG deficiency due to both immature liver function and undernutrition, and they may have "sick euthyroid syndrome". They may also be treated with drugs that suppress the hypothalamic-pituitary-thyroid axis. Drugs that suppress the hypothalamic-pituitary axis include known agents such as steroids and dopamine, aminophylline, caffeine and diamorphine, other commonly used in sick premature infants. Clinical Manifestations of Congenital Hypothyroidism Clinical findings are usually difficult to appreciate in the newborn period. Many of the classic features including, large tongue, hoarse cry, Blueprint in Pediatric Endocrinology 177

facial puffiness, umbilical hernia, hypotonia, mottling, cold hands and feet and lethargy are subtle and develop only with the passage of time. In addition, nonspecific signs that should suggest the diagnosis of neonatal hypothyroidism include: prolonged, unconjugated hyperbilirubinemia, gestation longer than 42 weeks, feeding difficulties, delayed passage of stools, hypothermia or respiratory distress in an infant weighing over 2.5 kg. A large anterior fontanelle and/or a posterior fontanelle > 0.5 cm is frequently present in affected infants but may not be appreciated. In general, the extent of the clinical findings depends on the cause, severity and duration of the hypothyroidism. Babies with congenital hypothyroidism are of normal size. However, if diagnosis is delayed, subsequent linear growth is impaired. The finding of palpable thyroid tissue suggests that the hypothyroidism is due to an abnormality in thyroid hormonogenesis or in thyroid hormone action. Diagnosis The diagnosis of neonatal hypothyroidism is confirmed by the demonstration of a decreased concentration of fT4 and an elevated TSH level (> 30 mU/L after one day of life) in serum. Bone age may be performed as a reflection of the duration and severity of the hypothyroidism in utero. A radionuclide scan (either iodine or pertechnetate) provides information about the location, size and trapping ability of the thyroid gland; ectopic thyroid glands, frequently sublingual, may be located anywhere along the pathway of thyroid descent from the foramen cecum to the anterior mediastinum. Thyroid imaging is helpful in verifying whether a permanent abnormality is present and aids in genetic counseling since thyroid dysgenesis is almost always sporadic condition whereas abnormalities in thyroid hormonogenesis tend to be autosomal recessive. Treatment of congenital hypothyroidism Replacement therapy with L-thyroxin should be begun as soon as the diagnosis of congenital hypothyroidism is confirmed. Both the initial treatment dose (10-15 μg/kg/day) and early onset of treatment (before 2 weeks) are important. In babies whose initial results on newborn screening are suggestive of hypothyroidism therapy should be begun immediately without waiting for the results of the confirmatory serum. 178 Chapter 5: Thyroid disorders in Children

. Treatment should not be delayed in anticipation of performing thyroid imaging studies as thyroxin is very precious to the astrocytes.

The aims of therapy are to normalize the fT4 as soon as possible, to avoid hyperthyroidism where possible, and to promote normal growth and development. Often small increments or decrements of L-thyroxin (12.5 μg) are needed. Current recommendations are to repeat the fT4 and TSH at 2 and 4 weeks after the initiation of L-thyroxin treatment, every 1-2 months during the first year of life, every 2-3 months between 1 and 3 years of age, and every 3-6 months thereafter until growth is complete. In hypothyroid babies in whom an organic basis was not established at birth and in whom transient disease is suspected, a trial off replacement therapy can be initiated after the age of 3 years when most thyroxin- dependent brain maturation has occurred. Whether or not premature infants with hypothyroxinemia should be treated remains controversial at the present time. Prognosis Although all are agreed that the mental retardation associated with untreated congenital hypothyroidism has been eradicated by newborn screening, controversy persists as to whether subtle cognitive and behavioral deficits remain, particularly in the most severely affected infants. Time to normalization of circulating thyroid hormone levels, the initial free T4 concentration, maternal IQ, socioeconomic and ethnic status have also been related to outcome. The long term problems for these babies appear to be in the areas of memory, language, fine motor, attention and visual spatial. Inattentiveness can occur both in patients who are over treated and those in whom treatment was initiated late or was inadequate. In addition to adequate dosage, assurance of compliance and careful long-term monitoring are essential for an optimal developmental outcome. Combined therapy with T4 and T3 offers no advantage to T4 alone. Causes of Hypothyroidism in Childhood and Adolescence Thyroiditis The broad category of thyroiditis includes the following inflammatory diseases of the thyroid gland: acute suppurative thyroiditis, which is due to bacterial infection; subacute thyroiditis (Riedel struma) Blueprint in Pediatric Endocrinology 179

which is rare in children results from viral infection of the gland; and chronic thyroiditis, which is usually autoimmune in nature. In childhood, chronic thyroiditis is the most common of these 3 types. Secondary thyroiditis may be due to the administration of amiodarone to treat cardiac arrhythmias or the administration of interferon-alpha to treat viral diseases. Acute Suppurative Thyroiditis It is uncommon and usually preceded by a respiratory infection. The left lower lobe is affected predominantly. The most common organism is Streptococcus viridans, followed by Staphylococcus aureus and pneumococcus. Recurrent episodes or detection of a mixed bacterial flora suggests that the infection arises from a thyroglossal duct remnant or, more often, from a piriform sinus fistula. Exquisite tenderness of the gland, swelling, erythema, dysphagia, and limitation of head motion are characteristic findings. Fever, chills, and sore throat are not uncommon, and leukocytosis is present. Isotope scanning of the thyroid gland often reveal decreased uptake in the affected areas. Thyroid function is usually normal, but thyrotoxicosis due to escape of thyroid hormone has been encountered in a child with suppurative thyroiditis resulting from Aspergillus. When abscess formation occurs, incision and drainage and administration of parenteral antibiotics are indicated. After the infection subsides, a barium esophagram or CT scan with contrast is indicated to search for a fistulous tract; if one is found, surgical excision is indicated. Usually is a transient cause of hypothyroidism. Subacute Thyroiditis (de Quervain Disease) It is rare in children. It is thought to have a viral cause and remits spontaneously. The disorder becomes manifested by an upper respiratory infection with vague tenderness over the thyroid and low-grade fever, followed by severe pain in the region of the thyroid gland. Inflammation results in leakage of preformed thyroid hormone from the gland into the circulation. Serum levels of fT4 and fT3 are elevated and mild symptoms of hyperthyroidism may be present, but radioiodine uptake is decreased. The erythrocyte sedimentation rate is increased. The course is variable, usually passing through a euthyroid to a hypothyroid phase; remission usually occurs in several months. Occasionally, this condition is superimposed on lymphocytic thyroiditis. 180 Chapter 5: Thyroid disorders in Children

Hashimoto’s Thyroiditis "Chronic Lymphocytic Thyroiditis (CLT)" Is the most common cause, both goitrous and non-goitrous hypothyroidism. The disease has a striking predilection for females and a family history of autoimmune thyroid disease. During childhood the most common age of presentation is adolescence, but the disease may occur at any age, even infancy. There is an increased prevalence of CLT in patients with insulin dependent diabetes mellitus, 20% of whom have positive thyroid antibodies and 5% of whom have an elevated serum TSH level. Hashimoto‘s thyroiditis may also occur as part of an autoimmune polyglandular syndrome as well, there is an increased incidence with certain chromosomal abnormalities (Down syndrome, Turner syndrome, Klinefelter syndrome and Noonan syndrome).CLT may be associated with chronic uriticaria and rarely with immune-complex glomerulonephritis. Antibodies to thyroglobulin (TG) and thyroid peroxidase (TPO), the thyroid antibodies measured in routine clinical practice, are detectable in over 95% of patients with CLT. Therefore, they are useful as markers of underlying autoimmune thyroid damage, TPO antibodies being more sensitive.TSH receptor blocking antibodies tend to occur only in patients with severe hypothyroidism. Goiter, present in approximately two-thirds of children with CLT results primarily from lymphocytic infiltration and in some patients, from a compensatory increase in TSH. The role of antibodies in goitrogenesis is controversial Children with CLT may be euthyroid, or may have subclinical or overt hypothyroidism. Occasionally, children may experience an initial thyrotoxic phase due to the discharge of preformed T4 and T3 from the damaged gland. Thyrotoxicosis may be due to concomitant thyroid stimulation by TSH receptor stimulatory antibodies (Hashitoxicosis). Most children who are hypothyroid initially remain hypothyroid, spontaneous recovery of thyroid function may occur, particularly in those with initial compensated hypothyroidism. On the other hand, some initially euthyroid patients will become hypothyroid with observation. Therefore, close follow up is necessary. The typical thyroid gland in CLT is diffusely enlarged and has a rubbery consistency. A palpable lymph Blueprint in Pediatric Endocrinology 181

node superior to the isthmus ‗Delphian node‘ is often found and may be confused with a thyroid nodule. Investigations Laboratory Tests in Thyroiditis . Acute thyroiditis: Laboratory abnormalities include leukocytosis with a left shift and an increased sedimentation rate. Thyroid function test results are within the reference range. . Subacute thyroiditis: The primary laboratory abnormalities are consistent with abnormal thyroid function. Initially, the thyroid- stimulating hormone (TSH) level is suppressed, and the free thyroxin (T4) level is increased. As the disorder progresses, transient or sometimes permanent hypothyroidism may develop. The WBC count is usually within the reference range but may be mildly elevated. High- sensitivity C-reactive protein levels are usually elevated in subacute thyroiditis. . Chronic thyroiditis: Laboratory abnormalities reflect thyroid function abnormality and evidence of autoimmunity. TSH levels are increased in children with subclinical and overt hypothyroidism. Free T4 levels are within the reference range in the former and low in the latter. In children with hyperthyroidism, TSH levels are suppressed. Many children have normal thyroid function and normal TSH levels. A diagnosis of CLT is made by the demonstration of elevated titers of anti- thyroglobulin (less sensitive and less specific) and/or anti-TPO antibodies and TSH receptor blocking antibodies. Imaging Studies . Radioactive iodine thyroid scanning: usually is not necessary for acute suppurative thyroiditis because the results are normal and do not aid in diagnosis. A scan may be helpful after diagnosis to identify a persistent thyroglossal duct as a route for infection. . This test is also unnecessary for chronic thyroiditis because the results can be misleading and may show increased uptake consistent with Graves's disease, a multinodular goiter, or a hypofunctioning or hyperfunctioning nodule. 182 Chapter 5: Thyroid disorders in Children

. Radioactive iodine thyroid scanning is helpful in patients with hyperthyroidism who are thought to have subacute thyroiditis because the extremely low uptake is consistent with the thyrocellular destruction in progress. . Thyroid ultrasonography is useful in revealing abscess formation in patients with acute thyroiditis. The degree of hyopoechogenicity on ultrasonography is related to the degree of thyroid dysfunction but its clinical use in chronic thyroiditis is questionable and does not alter management in children with chronic thyroiditis. Treatment of Thyroiditis . Acute thyroiditis requires immediate parenteral antibiotic therapy before abscess formation begins. For initial antibiotic therapy, administer penicillin or ampicillin to cover gram-positive cocci and the anaerobes that are the usual causes of the disease. In patients who are allergic to penicillin, cephalosporin is appropriate. In acute thyroiditis, surgery may be necessary to drain the abscess and to correct the developmental abnormality responsible for the condition. . Subacute thyroiditis is self-limiting; therefore, the goals of treatment are to relieve discomfort and to control the abnormal thyroid function. The discomfort can usually be relieved with low-dose aspirin (divided every 4-6 hourly). In the rare cases that aspirin does not relieve the discomfort, administer prednisone for 1 week and then taper. Propranolol can be used to reduce signs and symptoms of hyperthyroidism. Low-dose levothyroxine may be necessary in some patients who develop hypothyroidism. . Chronic autoimmune thyroiditis: Patients with overt hypothyroidism who have high thyroid-stimulating hormone (TSH) and low free T4 levels require treatment with levothyroxine. The dose is age dependent. TSH levels should be monitored and the dose should be adjusted to maintain levels within the reference range. Environmental Goitrogens Worldwide, iodine deficiency continues to be an important cause of hypothyroidism, affecting at least 800 million people living largely in developing countries. In addition, the child consumed a large intake of thiocyanate-containing foods that blocked organification of iodine. Blueprint in Pediatric Endocrinology 183

Iodine deficiency remains the most prevalent preventable cause of goiter and delayed intellectual development in the world today when dietary iodine intake is low, thyroxine secretion decreases and the compensatory increase in TSH causes thyromegaly. Naturally occurring goitrogens include cabbage, brussel sprouts, and turnips. It has been suggested that the process of cooking decreases the goitrogenic properties of these plants, and so it is notable that certain new nutritional supplements contain large quantities of freeze-dried Brassica vegetables. Foods that contain cyanogenic glucosides such as cassava may also contribute to goiter rates in iodine deficient regions. Tobacco smoking is associated with an increased prevalence of goiter, particularly in areas of iodine deficiency. Number of drugs used in childhood may affect thyroid function, including certain anticonvulsants, lithium, amiodarone, aminosalicylic acid, aminoglutethimide and sertraline. Both radioiodine therapy and thyroidectomy, occasionally used in childhood for the definitive treatment of Graves‘ disease, frequently cause permanent hypothyroidism. Secondary / Tertiary Hypothyroidism Secondary or tertiary hypothyroidism may develop as a result of acquired damage to the pituitary or hypothalamus, e.g., by tumors (particularly craniopharyngioma), granulomatous disease, head irradiation, infection (e.g. meningitis), surgery or trauma. Usually other trophic hormones are affected, particularly growth hormone. Thyroid Hormone Resistance In contrast to the neonatal period, children with thyroid hormone resistance usually come to attention when thyroid function tests are performed because of poor growth, hyperactivity, a learning disability or other nonspecific signs or symptoms. A small goiter may be appreciated. Affected patients have a high incidence of attention deficit hyperactivity disorder. Thyroid hormone resistance has also been described in patients with cystinosis. Clinical manifestations of Acquired Hypothyroidism The classical clinical manifestations include deceleration of growth which is usually the first clinical manifestation, but this sign often goes unrecognized, lethargy, cold intolerance, constipation, dry skin and hair texture, and periorbital edema. 184 Chapter 5: Thyroid disorders in Children

. School performance is not usually affected, in contrast to the severe irreversible neuro-intellectual sequelae that occur frequently in inadequately treated babies with congenital hypothyroidism. Goiter, which may be a presenting feature, typically is non-tender and firm, with a rubbery consistency and a pebbly surface. Osseous maturation is delayed, often strikingly, which is an indication of the duration of the hypothyroidism.

Fig. (5-4): Showed Goiter in 6 –Year-Old Boy. Adolescents typically have delayed puberty, whereas younger children may present with galactorrhea or pseudo precocious puberty. Galactorrhea is a result of increased TRH stimulating prolactin secretion. The precocious puberty, is thought to be the result of abnormally high TSH concentrations binding to the follicle-stimulating hormone receptor with subsequent stimulation. Delayed relaxation time of the deep tendon reflexes may be appreciated in more severe cases. There is an increased incidence of slipped femoral capital epiphyses in hypothyroid children. The combination of severe hypothyroidism and muscular hypertrophy which gives the child a ‗Herculian‘ appearance is known as the Kocher- Debre-Semelaign syndrome. In long-standing hypothyroidism, some children have headaches, visual problems and hyperplastic enlargement of the pituitary gland, as the result of thyrotroph hyperplasia and may be mistaken for a pituitary tumor. Additional features include nerve entrapment, ataxia, muscle weakness or cramps, menstrual disturbances, bradycardia, weight gain, and abnormal laboratory studies (hyponatraemia, macrocytic anemia, and hypercholesterolemia). Blueprint in Pediatric Endocrinology 185

Diagnosis of acquired hypothyroidism Measurement of TSH is the best initial screening test for the presence of primary hypothyroidism and free T4 will distinguish whether the child has subclinical (normal free T4) or overt (low free T4) hypothyroidism. Measurement of TSH, on the other hand, is not helpful in central hypothyroidism. In these cases hypothyroidism is demonstrated by the presence of a low free T4 accompanied by an inappropriately ‗normal‘ TSH. In the past TRH testing was sometimes utilized to distinguish a hypothalamic versus pituitary origin of the hypothyroidism.TRH is no longer available in the market. Thyroid hormone resistance is characterized by elevated levels of T4 and T3 and an inappropriately normal or elevated TSH concentration. Therapy of acquired hypothyroidism In contrast to neonatal hypothyroidism, rapid replacement is not essential in the older child. This is particularly true in children with long standing; severe thyroid under activity in which rapid normalization may result in unwanted side effects (deterioration in school performance, short attention span, hyperactivity, insomnia, and behavior difficulties).In these children it is preferable to increase the replacement dose slowly over several weeks to months. Severely hypothyroid children should also be observed closely for complaints of severe headache when therapy is initiated because of the rare development of pseudo tumor cerebri. In contrast, full replacement can be initiated at once without much risk of adverse consequences in children with mild hypothyroidism. Treatment of children and an adolescent with subclinical hypothyroidism (normal free T4, elevated TSH) is controversial. Treatment is recommended whenever the serum TSH concentration is >10 mU/L; however, if the TSH is between 5-10 mU/L treatment on a case by case basis is suggested. Replacement treatment with levothyroxine (50–150 μg daily) is indicated; fT4 and TSH should be measured after the child has received the recommended dosage for at least 6-8 weeks. Once a euthyroid state has been achieved, patients should be monitored every 3 to 6 months. Close attention is paid to interval growth and bone age as well as to the maintenance of a euthyroid state. Thyroid hormone replacement is not associated with significant weight loss in overweight children, unless the hypothyroidism is severe. Some children with severe, long standing hypothyroidism at diagnosis may not achieve their adult 186 Chapter 5: Thyroid disorders in Children

height potential even with optimal therapy, emphasizing the importance of early diagnosis and treatment. Treatment is usually continued indefinitely. Table (5-1): Showed Average Doses of Thyroxine Depending on Various ages.

Age Dose

0-3 months 12-15 mcg/kg/day

3-12 months 8-12 mcg/kg/da

1-5 years 6-8 mcg/kg/day

6-12 years 4-6 mcg /kg/day

Above 12 years 2-3 mcg/kg/day

Hyperthyroidism Transient Neonatal Hyperthyroidism Neonatal hyperthyroidism is almost always transient and results from the transplacental passage of maternal TSH receptor stimulating antibodies. Hyperthyroidism develops only in babies born to mothers with the most potent stimulatory activity in serum. This corresponds to 1- 2% of mothers with Graves‘ disease, or 1 in 50,000 newborns, an incidence that is approximately four times higher than is that for transient neonatal hypothyroidism due to maternal TSH receptor blocking antibodies. Although maternal TSH receptor antibody-mediated hyperthyroidism may present in utero, most often the onset is during the first week of life. This is due both to the clearance of maternally- administered antithyroid drug (propylthiouracil, methimazole or carbimazole) from the infant‘s circulation and to the increased conversion of T4 to the more metabolically active T3 after birth. Clinical Manifestations of Hyperthyroidism Fetal hyperthyroidism is suspected in the presence of fetal tachycardia (pulse greater than 160/min) especially if there is evidence of failure to thrive. In the newborn infant, characteristic signs and symptoms include tachycardia, irritability, poor weight gain, and prominent eyes. Goiter, when present, may be related to maternal Blueprint in Pediatric Endocrinology 187

antithyroid drug treatment as well as to the neonatal Graves‘ disease itself. . Rarely, infants with neonatal Graves‘ disease present with thrombocytopenia, jaundice, hepatosplenomegaly, and hypoprothrombinemia, a picture that may be confused with congenital infections such as toxoplasmosis, rubella, or cytomegalovirus. In addition, arrhythmias and cardiac failure may develop and may cause death, particularly if treatment is delayed or inadequate. In addition to a significant mortality rate that approximates 20% in some older series, untreated fetal and neonatal hyperthyroidism is associated with deleterious long-term consequences, including premature closure of the cranial sutures (cranial synostosis), failure to thrive, and developmental delay. The duration of neonatal hyperthyroidism, a function of antibody potency and the rate of their metabolic clearance, is usually 2 to 3 months but may be longer. Neonatal Thyrotoxicosis

Presentations include microcephaly, frontal bossing, intrauterine growth retardation, tachycardia, systolic hypertension leading to widened pulse pressure, irritability, failure to thrive, exophthalmos, goiter, flushing, vomiting, diarrhea, jaundice, thrombocytopenia, and cardiac failure or arrhythmias. Onset of neonatal thyrotoxicosis usually from immediately after birth to few weeks. Exclusively occurs in infants born to mothers with Grave's disease. Usually, Caused by transplacental passage of maternal thyroid stimulating immunoglobulin (TSI). . Occasionally, mothers are unaware that they have Grave's disease . If a mother has received definitive treatment (thyroidectomy or radiation therapy), the passage of TSI remains possible. . Disease usually resolves by age 3 to 6 months, during this time, treatment should be monitored regularly and doses should be adjusted according to the thyroid function test. Diagnosis The diagnosis of hyperthyroidism is confirmed by the demonstration of an increased concentration of circulating free T4 and fT3, accompanied by a suppressed TSH level in neonatal or fetal blood. 188 Chapter 5: Thyroid disorders in Children

Therapy In the fetus, treatment is accomplished by maternal administration of antithyroid medication. Until recently propylthiouracil (PTU) was the preferred drug for pregnant women, but current recommendations suggest the use of methimazole (MMI) rather than PTU after the first trimester because of concerns about potential PTU-induced hepatotoxicity. The goals of therapy are to utilize the minimal dosage necessary to normalize the fetal heart rate and render the mother euthyroid or slightly hyperthyroid. In the neonate, treatment is expectant. Either PTU (5 to10 mg/kg/day) or MMI (0.5 to 1.0 mg/kg/day) has been used initially in 3 divided doses. If the hyperthyroidism is severe, a strong iodine solution (Lugol‘s solution, 1 drop every 8 hours) is added to block the release of thyroid hormone immediately. Often the effect of PTU and MMI is not as delayed in infants as it is in older children. Therapy with both antithyroid drug and iodine is adjusted subsequently, depending on the response. Propranolol (1-2 mg/kg/day in 2 or 3 divided doses) is added if sympathetic overstimulation is severe, particularly in the presence of pronounced tachycardia. If cardiac failure develops, treatment with digoxin should be initiated, and Propranolol should be discontinued. Rarely, prednisone (2 mg/kg/day) is added for immediate inhibition of thyroid hormone secretion. Measurement of TSH receptor antibodies in treated babies may be helpful in predicting when antithyroid medication can be safely discontinued. Lactating mothers on antithyroid medication can continue nursing as long as the dosage of PTU or MMI does not exceed 400 mg or 40 mg, respectively. The milk/serum ratio of PTU is 1/10 that of MMI, a consequence of pH differences and increased protein binding, so one might anticipate less transmission to the infant, but concerns about potential PTU toxicity need to be considered. At higher dosages of antithyroid medication, close supervision of the infant is advisable. PTU in young children can induce liver failure leading to transplant and death. The risk of PTU-induced liver failure is about 1 in 2000 children. Unfortunately, routine biochemical surveillance of liver function will not be useful in identifying children who will develop PTU-induced liver failure. The only way to minimize the risk is to not use the drug. Blueprint in Pediatric Endocrinology 189

Permanent Neonatal Hyperthyroidism Rarely, neonatal hyperthyroidism is permanent and is due to gain of function mutation of the TSH receptor and should be suspected if persistent neonatal hyperthyroidism occurs in the absence of detectable TSH receptor antibodies in the maternal circulation. An autosomal dominant inheritance has been noted in many of these infants; other cases have been sporadic, arising from a de novo mutation. Early recognition is important because of irreversible sequelae, such as cranial synostosis and developmental delay may result. For this reason early, aggressive therapy with either thyroidectomy or even radioablation has been recommended. Causes of Hyperthyroidism in Childhood and Adolescence Graves’ disease

Fig. (5-5): Showed Classical Proptosis of 13-Year Old boy With Grave’s Disease.

More than 95% of cases are due to Graves‘ disease, an autoimmune disorder that, like CLT, is a complex genetic trait that occurs in a genetically predisposed population. There is a strong female predisposition, the female: male ratio being 6 - 8:1. Graves‘ disease is much less common in childhood than in the adult. Although it can occur at any age, it is most common in adolescence. Prepubertal children tend to have more severe disease, to require longer medical therapy and to achieve a lower rate of remission as compared with pubertal children. This appears to be particularly true in children who present at less than 5 years of age. Graves‘ disease has been described in children with other autoimmune diseases, both endocrine and non endocrine. These include diabetes mellitus, Addison‘s disease, vitiligo, systemic lupus erythematosis, rheumatoid arthritis, myasthenia gravis, periodic 190 Chapter 5: Thyroid disorders in Children

paralysis, idiopathic thrombocytopenia purpura and pernicious anemia. There is an increased risk of Graves‘ disease in children with Down syndrome. Graves‘ disease is caused by TSH receptor antibodies that mimic the action of TSH.

Rarely, hyperthyroidism may be caused by a functioning thyroid adenoma, by constitutive activation of the TSH receptor or it may be seen as part of the McCune Albright syndrome. Recently an adolescent female was described in whom hyperthyroidism resulted from an hCG-secreting hydatidiform mole. Hyperthyroidism also may be due to the inappropriate secretion of TSH by a pituitary adenoma but thyroid hormone resistance should be excluded. . Miscellaneous causes of transient thyrotoxicosis include the toxic phase of CLT, subacute thyroiditis and thyroid hormone ingestion (thyrotoxicosis factitia). Clinical Manifestations All but a few children with Graves‘ disease present with some degree of thyroid enlargement, and most have symptoms and signs of excessive thyroid activity, such as tremors, inability to fall asleep, weight loss despite an increased appetite, proximal muscle weakness, heat intolerance and tachycardia. Often the onset is insidious. Shortened attention span and emotional liability may lead to behavioral and school difficulties. Some patients complain of polyuria and of nocturia, the result of an increased glomerular filtration rate. Acceleration in linear growth may occur, often accompanied by advancement in skeletal maturation (bone age). Adult height is not affected. In the adolescent child, puberty may be delayed. If menarche has occurred, secondary amenorrhea is a common concomitant. If sleep is disturbed, the patient may complain of fatigue. Children with hyperthyroidism have a lower remission rate than adults, 15%-30% remission rate with two or more years of antithyroid drugs. Remissions can be predicted by certain clinical evidence; for example a small thyroid with normal TSI in an older child are favorable factors that do not predict a remission of the disease, while a large thyroid with elevated TSI in a young toddler are unfavorable predictors of remission. Blueprint in Pediatric Endocrinology 191

Examination Physical examination reveals a diffusely enlarged, soft or "fleshy" thyroid gland, smooth skin and fine hair texture, excessive activity, and a fine tremor of the tongue and fingers. A thyroid bruit may be audible. In contrast, the finding of a thyroid nodule suggests the possibility of a toxic adenoma. The hands are often warm and moist. Tachycardia, a wide pulse pressure, and a hyperactive precordium are common. Café au lait spots, particularly in association with precocious puberty, on the other hand, suggests a possible diagnosis of McCune Albright syndrome while if a goiter is absent, thyrotoxicosis factitia should be considered. The ophthalmopathy characteristic of Graves‘ disease in adults is considerably less common in children, although a stare and mild proptosis are observed frequently. Diagnosis The clinical diagnosis of hyperthyroidism is confirmed by the finding of increased concentrations of circulating thyroid hormones free T4 and suppressed TSH. The diagnosis of Graves‘ disease is confirmed by the demonstration of TSH receptor antibodies in serum. Thyroglobulin and thyroid peroxidase enzyme (TPO) antibodies are positive in 70% of children and adolescents with Graves‘ disease but their measurement is not as sensitive or specific as measurement of TSH receptor antibodies. In contrast to adults, radioactive iodine uptake and scan are used to confirm the diagnosis of Graves‘ disease only in atypical cases (for example, if measurement of TSH receptor antibodies is negative, or if a functioning thyroid nodule is suspected). Treatment The choice of the three therapeutic options (medical therapy, radioactive iodine, or surgery) to use, should be individualized and discussed with the patient and his / her family. Each approach has its advantages and disadvantages with respect to efficacy, both short and long term complications, the time required to control the hyperthyroidism, and the requirement for compliance. In general, medical therapy is the initial choice of most pediatricians although radioiodine is gaining increasing acceptance.

192 Chapter 5: Thyroid disorders in Children

Medical Therapy The thiouracil compounds PTU, MMI and carbimazole (converted to MMI) exert their antithyroid effect by inhibiting the organification of iodine and the coupling of iodotyrosine residues on the thyroglobulin molecule to T3 and T4. MMI is generally preferred over PTU because for an equivalent dose it requires taking fewer tablets, it has a longer half-life and because it has a more favorable safety profile. Recent reports have suggested that the risk of hepatotoxicity with PTU may be greater in the young; leading to the recommendation that PTU be used only in pediatric patients who are allergic to MMI, PTU use has also been advocated in the first trimester of pregnancy. Since PTU but not MMI inhibits the conversion of T4 to the more active isomer T3, PTU may have a role in the treatment of thyroid storm and/or if the thyrotoxicosis is severe. The initial dosage of MMI is 0.5-1 mg/kg/day given every 12 hours and of PTU is 5 -10 mg/kg/day given every 8 hours. In severe cases, a beta- adrenergic blocker 1-2 mg/kg/day daily or twice daily) can be added to control the cardiovascular over activity until a euthyroid state is obtained. Patients should be followed every 4 to 6 weeks until the serum concentration of free T4 normalizes. It should be noted that the TSH concentration may not return to normal until several months later. Therefore, measurement of TSH is useful as a guide to therapy only after it has normalized but not initially. Once T4 and T3 have normalized reduction of the dose by 30% to 50% is indicated. Toxic drug reactions (erythematous rashes, uriticaria, arthralgia, transient granulocytopenia, (<1500 granulocytes/mm3), have been reported in 5% to 14% of children. Rarely, more severe sequelae, such as hepatitis, a lupus like syndrome, thrombocytopenia, and agranulocytosis, (<500 granulocytes/mm3) may occur. Most reactions are mild and do not contraindicate continued use. The risk of agranulocytosis appears to be greatest within the first 3 months of therapy but it can occur at any time. Routine monitoring of liver function tests is not usually recommended. It is important to caution all patients to stop their medication immediately and consult their physician should they develop unexplained fever, sore throat, or gingival sores or jaundice. Unlike PTU, MMI is rarely associated with hepatocellular injury. Approximately 10% of children treated medically will develop long term hypothyroidism, a consequence of coincident cell and cytokine-mediated destruction and/or the development of TSH receptor blocking antibodies. Blueprint in Pediatric Endocrinology 193

. PTU should not be used as a first line treatment in children. . PTU use in children should be only considered in rare circumstances, such as preparation for surgery in a patient allergic to MMI. Radioactive Iodine Radioactive iodine therapy should be used with caution in children less than ten years of age and particularly in those less than five years of age because of the increased susceptibility of the thyroid gland in the young to the proliferative effects of ionizing radiation. Pretreatment with antithyroid drugs prior to RAI therapy is advisable if the hyperthyroidism is severe. Thyroid hormone concentrations may be raised transiently 4 to 10 days after RAI administration due to the release of thyroid hormones from the damaged gland. Beta blockers may be useful during this time period. Similarly, analgesics may be employed if there is mild discomfort due to radiation thyroiditis. Other acute complications of RAI therapy (nausea, significant neck swelling) are rare. One usually sees a therapeutic effect within 6 weeks to 3 months. Worsening of ophthalmopathy, described in adults after RAI, does not appear to be common in childhood. However, if significant ophthalmopathy is present RAI therapy should be used with caution and pretreatment with steroids may be effective. Surgery Surgery, is performed less frequently now than in the past. An advantage of this form of therapy is the rapid resolution of the hyperthyroidism. Near-total thyroidectomy is the procedure of choice in order to minimize the risk of recurrence. Surgery usually is reserved for patients who have failed medical management, who have a markedly enlarged thyroid, who refuse radioactive iodine therapy, and for the rare patient with significant ophthalmopathy in whom radioactive iodine therapy is contraindicated. The most common potential complication is transient hypocalcaemia which occurs in approximately 10% of patients. Other, less common potential complications are keloid formation (2.8%), recurrent laryngeal nerve paralysis (2%), hypoparathyroidism (2%), and, rarely (0.08%). Prior to surgery, it is important to treat with antithyroid medication in order to render the child euthyroid and prevent thyroid storm. Iodides (Lugol‘s solution, 5 to 10 drops TID or potassium iodide) 194 Chapter 5: Thyroid disorders in Children

are added for 7 to 14 days prior to surgery in order to decrease the vascularity of the gland. Key Points Graves's Disease . Physical exam usually reveal a diffuse goiter, a feeling of grittiness and discomfort in the eye, retrobulbar pressure or pain, eyelid lag or retraction, periorbital edema, chemosis, scleral injection, exophthalmos, extra ocular muscle dysfunction, localized dermopathy, and lymphoid hyperplasia . Peak incidence is between ages of 11–15 years . Female-to-male ratio is 5: 1 . Family history of autoimmune thyroid disease is usually present . Autoimmune disease (positive TSI, may also have low titers of thyroglobulin and microsomal antibodies) . Laboratory findings of raised levels of free thyroxin, triiodothyronine with suppressed level of TSH . Increased I123 uptake distinguishes from Hashimoto‘s thyroiditis. . Methimazole is the first choice. . Propylthiouracil (PTU) should not be used as first-line treatment, as of few reported cases of fatal hepatitis. . Radioactive iodine or surgical thyroidectomy is other options for refractory cases in pediatrics. Goiter Goiter is enlargement of the thyroid gland. Causes . Physiological . During pubertal age . Immunological o Chronic lymphocytic thyroiditis (Hashimoto thyroiditis) Blueprint in Pediatric Endocrinology 195

o Graves disease o Amyloid deposition (familial Mediterranean fever, juvenile rheumatoid arthritis) . Infectious o Acute suppurative thyroiditis (most often Streptococcus o pyogenes, Staphylococcus aureus, and Streptococcus pneumoniae) o Subacute thyroiditis (often viral) . Environmental o Goitrogens: Iodide, lithium, amiodarone, oral contraceptives, perchlorate, cabbage, soybeans, o Thiocyanate o Iodine deficiency . Neoplasia (Rare in children) o Thyroid adenoma/carcinoma o Medullary carcinoma: 4%-10% as part of the MEN-2 o TSH-secreting adenoma o Lymphoma . Congenital (usually very rare) o Dyshormonogenesis o Thyroid hormone resistance (RTH) . Miscellaneous o Multinodular goiter Resistance to Thyroid Hormone (RTH) Is usually dominantly inherited end-organ responsiveness to TH was identified in 1967. It is a rare disease. Incidence is estimated as 1 in 40,000-50,000 live births. The most common cause of the syndrome is mutations of the β subunit (THRB gene) of the thyroid hormone receptor, of which over 100 different mutations have been documented. The recent 196 Chapter 5: Thyroid disorders in Children

discoveries of genetic defects that reduce the effectiveness of thyroid hormone through altered cell membrane transport and metabolism have broadened the definition of thyroid hormone insensitivity to encompass all defects that can interfere with the biological activity of a chemically intact hormone secreted in normal amounts. Clinical Features Presenting symptoms and signs are goiter, hyperactive behavior, learning disabilities, developmental delay and sinus tachycardia. The finding of elevated serum fT4 levels in association with non suppressed TSH usually leads to the diagnosis. They have a variable refractoriness to hormone action in peripheral tissues. The majority of subjects maintain a normal metabolic state at the expense of high thyroid hormonal (TH) levels. This compensation for the hyposensitivity to TH is variable not only among individuals but also in different tissues. As a consequence, clinical and laboratory evidence of TH deficiency and excess often coexist. For example, delayed growth and bone maturation and learning disabilities, suggestive of hypothyroidism, can be present along with hyperactivity and tachycardia, compatible with thyrotoxicosis. Frank symptoms of hypothyroidism are more common in individuals who have received treatment to normalize their circulating TH levels. Diffuse goiter is the most common finding, reported in 66-95% of cases. Sinus tachycardia is also very common, which, together with goiter, often lead to the erroneous diagnosis of autoimmune thyrotoxicosis. Fifty percent of children with RTH have some degree of learning disability with or without attention deficit hyperactivity disorder. In contrast, the occurrence of RTH in children with attention deficit disorder is extremely rare. One-quarter have intellectual quotients (IQ) less than 85% but frank mental retardation (IQ < 60) was found only in 3% of cases. Deaf-mutes and color blindness occurred in all three affected members of a single family with TRß gene deletion. Types Two major forms: asymptomatic individuals with generalized resistance (GRTH) and patients with thyrotoxicosis features, suggesting predominant pituitary resistance (PRTH). Blueprint in Pediatric Endocrinology 197

Diagnosis

In the untreated subject, high serums free T4 concentration and nonsuppressed TSH important for the diagnosis of RTH. Serum fT4 and fT3 values can be just above to several folds of the upper limits of normal. Serum thyroglobulin concentration tends also to be high; reflecting the level of TSH induced thyroid gland hyperactivity. TSH has relatively high bioactivity, which explains the development of a TSH- induced goiter despite normal levels of immunoreactive TSH. Thyroidal radioiodide uptake is high and not dischargeable by perchlorate. Antibodies to thyroperoxidase and thyroglobulin are usually negative but when present, they are indicative of coexistent autoimmune thyroid disease. The characteristic blood test results for this disorder can also be found in other disorders (for example TSH-oma (pituitary adenoma), or other pituitary disorders). The diagnosis may involve identifying a mutation of the thyroid receptor, which is present in approximately 85% of cases. . Characteristic of the RTH syndrome is the paucity of specific clinical manifestations are variable from one patient to another. . Presenting symptoms and signs are goiter, hyperactive behavior, learning disabilities, developmental delay and sinus tachycardia. . The finding of elevated serum TH levels in association with nonsuppressed TSH usually leads to the diagnosis . . As a consequence, clinical and laboratory evidence of TH deficiency and excess often coexist. For example, delayed growth and bone maturation and learning disabilities, suggestive of hypothyroidism, can be present along with hyperactivity and tachycardia, compatible with thyrotoxicosis. . Goiter is by far the most common finding, Enlargement is usually diffuse. Nodularity and gross asymmetry occurs in goiters recurring after surgery. . Sinus tachycardia is also very common, which, together with goiter, often lead to the erroneous diagnosis of autoimmune thyrotoxicosis . About one-half of subjects with RTH have some degree of learning disability with or without attention deficit hyperactivity disorder. 198 Chapter 5: Thyroid disorders in Children

In contrast, the occurrence of RTH in children with attention deficit disorder is extremely rare. One quarter have intellectual quotients (IQ) less than 85% but frank mental retardation (IQ <60) was found only in 3% of cases . Deaf-mutism and color blindness occurred in all three affected members of a single family with TRß gene deletion Treatment Increased endogenous TH may not be sufficient to supply the requests of peripheral tissues, especially in infants with GRTH. Although general criteria for treatment of infants with GRTH is still lacking, in young children presenting with growth and/or mental retardation, the administration of supraphysiological doses of L-T4 may be beneficial to overcome the high degree of resistance in some tissues. It is evident that such therapy needs careful monitoring in order to avoid overtreatment. In this respect, particular attention has to be paid to TSH levels, as well as to a number of indices of peripheral TH action and pituitary MRI, as previously discussed. No alternative treatment to L-T4 administration has been so far discovered. Inutero Diagnosis & Treatment Although the diagnosis of RTH is now possible both in utero and at birth, the indications for treatment of fetuses and newborns are still under investigation. In fetuses with RTH who are small for gestational age, an indication to the treatment can be envisaged. Since Triiodothyroacetic acid (TRIAC) has been documented to cross the placental barrier, administration of this analog to the mother may be undertaken only after molecular confirmation of RTH in the fetus in newborns; retarded bone development and failure to thrive indicate the need of L-thyroxin administration at supraphysiological doses. Various Suggested Treatments Several agents acting at various levels have been suggested in the past for the treatment of RTH, in particular PRTH. . Lowering serum thyroid hormone levels by antithyroid drugs invariably causes dramatic increase of TSH levels followed by a consistent increase in goiter size and possible pituitary hyperplasia. This approach should be therefore avoided or considered as the last resort. Blueprint in Pediatric Endocrinology 199

. Administration of T3 was also suggested, but this produces daily peaks of high levels of T3, which may maintain signs, and symptoms of thyrotoxicosis. . Corticosteroids constantly cause severe inhibition of hypothalamic-pituitary-adrenal axis function and Cushingoid features. In order to avoid side effects of steroid, alternative day prednisolone therapy (1-2 mg/kg/ day) have been used in my patients with remarkable suppression and improvement in height (I personally recommend alternative daily therapy in difficult cases). . Furthermore, trials with either the dopaminergic drugs, such as Bromocriptine, or somatostatin analogs have been performed, but it appears that during a prolonged administration, all these drugs rapidly lose their efficacy in reducing TSH levels, and therefore the TH hypersecretion. In particular, somatostatin analogs appear extremely useful in controlling signs and symptoms of hyperthyroidism in patients with TSH-secreting pituitary adenoma. On the contrary, except for the first few days after injection, RTH patients rapidly escape from the inhibitory effect on TSH secretion. . The rationale for vitamin A treatment is that of enhancing the availability of retinoid, in particular 9-cis-retinoic acid which dimerizes with TRb in binding to TH receptor response elements (TREs) on gene controlled by TH, thus augmenting the action of thyroid hormones on gene expression. Future of RTH Therapy Molecular engineering provided novel therapeutic approaches based on the ability to clone individual types of gene, transfer them into recipient cells and express them, or to design new proteins, or even to inhibit specifically the expression of a predetermined and characterized gene in vivo. It is possible to speculate that genetic strategies prompted to inhibit mutated TRb gene expression may be considered as a specific and individual therapy for RTH patients. . TRIAC is first line therapy in almost all patients. . Bromocriptine has a transient effect owing to TSH escape from inhibition. 200 Chapter 5: Thyroid disorders in Children

. Corticosteroid every other day is an alternative therapy in my local cases with remarkable improvements in clinical and laboratory follow- up.. . Antithyroid drugs cause of further increase in TSH circulating level with consequent increase of goiter size and to hyperplasia at pituitary thyrotrophs level . β- Blockers effects limited to β-adrenergic blockade. Propranolol inhibits peripheral conversion of T4 to T3, worsening of tissue hypometabolic state. Cardiac selective compounds, such as atenolol devoid of effect on peripheral T4 conversion, appear to be more useful. Further Reading

1. Birrell, G. & Cheetham, T. (2004) Juvenile thyrotoxicosis; can we do better? Archives of Disease in Childhood 89, 745–750. 2. Brown, R.S. (2001) The thyroid gland. In: Clinical Paediatric Endocrinology (ed. C.G.D. Brook & P.C. Hindmarsh), 4th edn, pp 288–320. Blackwell Science, Oxford. 3. Haddow, J.E., Palomaki, G.E., Allan, W.C. et al. (1999) Maternal thyroid deficiency during pregnancy and subsequent neuropsychological development in the child. New England Journal of Medicine 341, 549–555. 4. LaFranchi, S (2004) Disorders of the thyroid gland. In: Nelson’s Textbook of Pediatrics (ed. R.E. Behrman, R.M. Kliegman & H.B. Jenson) 17th edn, pp 1870– 1889. Saunders, Philadelphia. 5. Kelnar, C.J.H. & Butler, G.E. (2003) Endocrine gland disorders. In: Forfar and Arneil‘s Textbook of Paediatrics (ed. N. McIntosh, P. Helms & R. Smyth) 6th edn, pp 443–559. Churchill Livingstone, London. 6. Ogilvy-Stuart, A.L. (2002) Neonatal thyroid disorders-a review. Archives of Disease in Childhood 87, F165–F171. 7. Osborn, D.A. (2001) Thyroid hormones for preventing neurodevelopmental impairment in preterm infants. Cochrane Database Systematic Review (4): CD001070. 8. Rovet, J. (2003) Long term follow up of children born with sporadic congenital hypothyroidism. Annals of Endocrinology 64,1:58–61.

Chapter 6

Growth and Growth Disorders

. Introduction . Hormonal influences on fetal growth . Factors determining normal growth depend on the child's age . Growth assessment . Short stature . Causes of short stature o Normal variant o Familial short stature o Constitutional delay of growth and puberty o Pathological short stature o Small gestational age o Idiopathic short stature o Psychosocial deprivation and retardation of growth o Skeletal dysplasia o Chronic illness affecting growth o Rickets o SHOX deficiency syndromes o Malnutrition o Malabsorption / Gastrointestinal Diseases o Syndromes associated with short stature . Turner's syndrome . Noonan's syndrome . Russell-Silver Syndrome . Seckel's bird headed dwarfism . Down syndrome (Trisomy 21) . Prader-Willi syndrome . DiGeorge syndrome . Growth hormone deficiency . Congenital GH deficiency . Hypothalamic–Pituitary Malformations . Hereditary GH Deficiency o GH1 gene

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o GHRH Receptor . Congenital structural CNS defects . CNS Tumors o Craniopharnygioma . Cranial irradiation . Diagnostic approach to child with short stature o History o Examination o Growth velocity . Laboratory evaluation of short stature o GH stimulation tests o Serum markers of GH secretion o Other possible tests o Indications of GH testing in children . Growth hormone therapy . Adverse effects of rhGH treatment . Monitoring GH therapy . Defining the Response to GH Treatment . The Role of GH Treatment Alternatives o Anabolic steroids o IGF-1 therapy o GnRH analogs o Aromatase inhibitors . Psychological counseling . Growth hormone insensitivity . Post-receptor forms of GH insensitivity . IGF-1 gene abnormalities . IGF-binding protein abnormalities . IGF-1 receptor gene abnormalities . Diagnosis & treatment of Primary IGF-1 deficiency . Overgrowth in the fetuses . Soto's syndrome (cerebral gigantism) . Tall stature o Differential diagnosis of tall stature o Diagnosis o Management of tall stature

Introduction

Growth is a dynamic process in which increasing cell size and number in various tissues result in a physical increase in the size of the body as a whole. Simultaneously, development occurs as tissues differentiate in form and mature in function, reflecting the person's genetic heritage and environmental interactions. Growth is not a static process and is subjected to many variables including; genetics, nutrition, general health, endocrine status, psychological factors and puberty. Hormonal Influences on Fetal Growth Neither growth hormone nor thyroid hormones are important regulators of fetal growth. Insulin has a major effect on growth and size at birth, mostly during the third trimester when it stimulates fetal lipogenic activity, including a rapid accumulation of adipose tissue. Insulin induces protein synthesis and hepatic glycogen deposition, increases nutrient uptake and utilization, and has a direct anabolic effect. The placental lactogen, a structural related placental peptide that has many GH-like actions, also seems to play an important role in fetal growth. Maternal serum concentrations of placental lactogen rise significantly in the third trimester, parallel with a rise in serum IGF-1. IGF-1 and IGF-2, which in the fetus function independently of pituitary GH also have important effects on the growth and differentiation of various tissues. Recent studies have shown that leptin, the product of the ob gene, a hormone produced in adipose tissue, may play a role in the nutritional homeostasis of the fetus and in fetal growth. The hormone has been detected in fetal blood as early as the 18th week of gestation. Factors Determining Normal Growth Depend on the Child's age . The major determinants of fetal growth are uterine size, placental function, maternal nutrition, insulin, insulin-like growth factors (IGFs), and IGF-binding proteins (IGFBPs). . Postnatal growth is characterized by an initial rapid growth rate that declines progressively, reaching a plateau of about 5 to 7 cm / year between three years of age until puberty. Babies born large or small for

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their genetic potential will 'channel' to their correct percentile in their first two years. Growth hormone, thyroid hormones, nutrition, and insulin play major roles at this time. . Pubertal growth, which happens immediately prior to puberty, growth usually, slows down ('prepubertal dip'), only to be followed by the pubertal growth spurt. . Sex hormones exert important growth effects during puberty, in addition to other factors such as growth hormone, thyroid hormones, nutrition, and insulin. Girls have their growth spurt early in puberty. Boys experience their growth spurt towards the end of puberty and achieve greater height velocities than girls. This, combined with the fact that boys grow for approximately 2 years more than girls, explains the 13 cm difference in final heights between the sexes. Growth Assessment It is important to assess serial measurements plotted on a growth chart. Care must be taken to plot the height and weight based on the child's actual chronological age, ideally on ethnic-specific charts. Length should have been measured supine in infants until the age of two years and standing thereafter. Ideally, measurements should be made using a device such as a Harpenden stadiometer and by the same measurer on consecutive occasions so as to reduce inter-observer error. Pathological growth should always be considered in children who do not grow well regardless of height. Any child who falls behind in growth across major percentiles in the chart should be evaluated, even when the height is not below the 3rd percentile. Growth progression over a long period of time is more informative than based on shorter periods of time. The growth rate varies according to the seasons, generally being fastest in the spring and summer. The growth progression should be evaluated over a period of at least 6 months to 1 year. In addition, there is a great variation in the growth at different stages of life. In the first year of life, linear growth is very fast: a total of approximately 25 cm is gained. In the second year of life it is 12.5 cm/year, in the third through fourth years 7 cm/year, and in the fifth through sixth years 6 cm/year. From then on to puberty it is 5 cm/year. Guidelines for abnormal growth rates adjusted for chronological age are as follows: fewer than 7 cm/year under age 4 years, fewer than 6 cm before age 6, and fewer than 4.5 cm from 6 years until puberty. At Blueprint in Pediatric Endocrinology 205

this stage growth acceleration ensues. Pubertal growth spurt occurs during early puberty and before menarche in girls (Tanner stages 2-3), during which time they grow at a mean velocity of 10.3 cm per year. The pubertal growth period is longer in boys than in girls. The growth data of each patient must be plotted on the appropriate chart for that particular child. Growth velocity charts may be helpful because these take into account different stages of growth such as pubertal growth spurt. The genetic potential of the child should be considered in the evaluation of the present growth pattern. Any deviation from the expected height for the family should be worrisome. For this purpose, formulas and standards for target height for the family and predicted adult height have been developed. A child's target height is calculated as follows: in girl (height of mother in cm + height of father in cm – 13 cm) / 2, while in boy (height of mother in cm+13 cm + height of father in cm) / 2. The target height obtained by this method is then applied to the last line of the gender- appropriate growth chart. The projected height is determined by extrapolating the child‘s growth along his or her own channel. If the projected final height is within 5 cm of target or midparental height, the child‘s height is appropriate for the family. On the other hand, if the difference between the target and the projected height is more than 5 cm, a pathological cause should be considered. In order to assess properly the predicted adult height, accurate bone maturation patterns are necessary. The two most commonly used methods of assessing the maturation or skeletal age are the Greulich and Pyle (GP) and the Tanner-Whitehouse (TW2) methods. The GP method of assessing bone age is usually done by comparing an x-ray film of the frontal view of the left hand and wrist with given standards of the GP atlas. The advantage of the TW2 method over the GP method is that it appears to be more objective. Moreover, it can differentiate bone age up to one-tenth of a year, whereas the GP method gives only a rough approximation, with intervals of 6–12 months between the standards. Thus, the TW2 method is more sensitive in following small changes in bone age, but it is more time-consuming and few clinicians used it. The bone maturation pattern is also helpful in differentiating the type of short stature. The bone growth in children with constitutionally delayed growth is slightly retarded (2, or at the most, 3 years), and it is usually 206 Chapter 6: Growth and Growth Disorders

proportional to height. When adolescence begins and the growth spurt occurs, the bone age increases proportionally to height. The bone age in patients with familial or genetic short stature is seldom retarded more than 1 year compared with chronological age, and it usually follows a normal maturation pattern. In contrast, there may be a marked bone age delay in children with pathological short stature, such as hypothyroidism, growth hormone deficiency, or chronic disease. The bone age may be even further behind than that expected for height. A short adolescent with sexual infantilism and a bone age maturation delay greater than 3 years is more likely to have pathological short stature, such as that caused by hypopituitarism or hypothyroidism. The degree of the delay may also reflect the length of time the patient has had the disease. Determination of the upper and lower body segment is also essential. This can be done by measuring the distance between the upper border of the symphysis pubis and the floor in a patient who is standing against a flat wall in the proper position for height measurement. This measurement is difficult to obtain accurately, because the superior border of the symphysis pubis is not easy to locate and palpate, particularly in some obese patients. Preferably, the sitting height can be measured to represent the upper segment, using a Harpenden sitting table. Conditions that cause disproportionate limb shortening include skeletal dysplasia for example, achondroplasia, and hypochondroplasia. On the other hand, the trunk height may be disproportionally shorter than the limbs in scoliosis or in spondyloepiphyseal dysplasia. Short Stature Is defined as height below the third percentile (- 2 SDS); therefore, 3% of normal children would be classified as being short. ‗‗Dwarfism,‘‘ the severe form of short stature, is defined as height below 3 standard deviations (SD) from the mean. A number of different reference charts have been used, most popular are charts published by the Center for Disease Control and Prevention (CDC) (www.cdc.gov/growthcharts). Saudi, local growth charts are also available (www.mohe.gov.sa). . Accurate measurements, using correct age- and sex-specific growth charts, are mandatory. . Care must be taken to plot the height and weight based on the child's actual chronological age. Blueprint in Pediatric Endocrinology 207

. Growth velocity determines the change in height over time. It is calculated as the difference in height on 2 different occasions over 1 year. . Growth velocities depend on age and pubertal status. . Height that plots stably along a given percentile on the growth chart reflects normal growth velocity. . Crossing percentiles in a downward direction reflects poor growth velocity. Causes of Short Stature Normal Variant Familial Short Stature (genetic short stature) These children are short throughout life and are short as adults, but characteristically they grow at normal rates in their own percentile; however, their height is within normal limits when allowance is made for parental heights. Children with familial short stature usually have parents or close relatives who are short. They often have normal birth weight and length but their growth rate declines during the first 2 to 3 years of life. Their growth curve subsequently parallels the normal curve but falls below the fifth percentile. Their bone age is approximately equal to their chronological age but less than their height age. These children usually enter puberty at the appropriate age Constitutional Delay of Growth and Puberty (CDGP) Is the most common cause of delayed growth and sexual development. This diagnosis constitutes a large proportion of the growth disorders seen by pediatric endocrinologists. This entity is characterized by short stature as a variant of normal growth. These patients are the typical ‗‗slow growers‘‘ and ‗‗late bloomers,‘‘ with a familial prevalence. Often it is recognized long before adolescence, when sexual development is not yet a concern. The child with constitutional delay of growth and development typically is characterized by a deceleration of growth occurring during the first 2 years of life, followed by normal growth progression paralleling a lower percentile curve throughout the rest of the prepubertal years, until a late catch-up growth or growth spurt occurs in adolescence. Fathers usually report a similar pattern of growth and delayed puberty. Patients with constitutional growth delay usually follow 208 Chapter 6: Growth and Growth Disorders

a familial pattern of growth; growth delay is itself inherited from multiple genes from both sides of the family. There may be no short stature in the family, but there may be similar growth patterns. Usually it occurs in boys, only occasionally in girls. The diagnosis of constitutional growth delay in girls should be made only after eliminating other possibilities of pathological growth patterns. Of interest is that in developing countries suboptimal nutrition was shown to produce a growth pattern similar to that of constitutional growth delay. In children with growth failure due to primary malnutrition, when the nutritional intake improved, growth resumed at a lower percentile, as in patients with constitutional growth delay. Once there was down regulation of the growth, the patients canalized their growth at a lower level than that before the nutritional insult. Patients with constitutional growth delay may also show an apparent deviation from the normal curve sometime between 10 and 14 years. However, this may represent merely the difference between the prepubertal child with constitutional delay of growth and development and the average child already having a pubertal growth spurt. There is also a 2–4 year delay in skeletal maturation, retarded sexual development, and a 60–90% incidence of a familial history of delayed growth and pubertal development. IGF-1 levels tend to be low for chronological age but within the normal range for bone age. Growth hormone responses to provocative testing tend to be lower than in children with a more typical timing of puberty. The prognosis for normal adult height in these children is guarded. Predictions based on height and bone age tend to overestimate eventual height to a greater extent in boys than in girls. Boys with more than 2 yr of pubertal delay may benefit from a short course of testosterone therapy to hasten puberty after 14 yr of age. The cause of this variant of normal growth is thought to be persistence of the relatively hypogonadotrophic state of childhood. Pathological Short Stature Pathological short stature is the least frequently occurring but most serious cause of short stature. Pathological short stature should be suspected in children who do not grow normally, those with a growth velocity of less than 4 cm/year after 6 years of age, and in those with marked short stature. Bone maturation is usually quite delayed, often behind that expected for height.

Blueprint in Pediatric Endocrinology 209

Small Gestational Age (SGA) It has been defined most commonly as a birth weight of under the 10th percentile for the gestational age. It is especially important because of the higher incidence of morbidity and mortality in such children and the potential long-term complications of SGA in adults. Although some SGA may grow and develop normally and attain normal stature as adults, about 10–15% do not exhibit catch-up growth and remain short throughout life. SGA who have not caught up in height by the age of 2 years, but are otherwise healthy have frequently been categorized as having ―primordial growth failure.‖ These children also have resistance to the action of the GH-IGF axis, which also may lead to insulin resistance. It is a clinically important diagnosis and also an indication for GH treatment after the age of 3 years, despite no documented GH deficiency. It is usually in these children no GH provocative testing is needed. Idiopathic Short Stature (ISS) Heterogeneous group of children consisting of many presently unidentified causes of short stature. It is estimated that approximately 60–80% of all short children. It is defined as a condition in which the height of an individual is more than 2 SD score (SDS) below the corresponding mean height for a given age, sex, and population group without evidence of systemic, endocrine, nutritional, or chromosomal abnormalities. Children with ISS have normal birth weight and are GH sufficient. Treatment with GH for selected group of patients has been FDA approved, despite no documented GH deficiency. The FDA approves GH for the treatment of ISS if the height is less than or equal to 2.25 SD (~1st percentile), the predicted adult height falls below the normal range, epiphyses are open, and other causes of short stature are excluded. Endocrine Causes Include GH deficiency, hypothyroidism, Cushing‘s disease (endogenous or exogenous), and pseudohypoparathyroidism. Children with GH deficiency are having severe short stature (height >3 standard deviation scores below mean for population, their height more than 2 SDS below mean and a growth velocity over 1 year of more than 1 SDS below mean or a decrease in the height SDS of more than 0.5 over 1 year 210 Chapter 6: Growth and Growth Disorders

in children over 2 years of age, Height SDS more than 1.5 SDS below target height SDS, Height velocity more than 2 SDS below mean over 1 year or more than 1.5 SDS over 2 years in the absence of short stature with delayed bone age. It is also important to remember that pituitary hormone deficiencies can evolve, so regular monitoring, both clinically and with investigations, is needed. Primary hypothyroidism is more common than GH deficiency. Low free T4 and elevated TSH levels establish the diagnosis. Responses to GH provocative tests may be subnormal, and enlargement of the sella turcica may be present. Pituitary hyperplasia recedes during treatment with thyroid hormone. Because thyroid hormone is a necessary prerequisite for normal GH synthesis, it must always be assessed before GH evaluation. Psychosocial Deprivation Emotional deprivation is an important cause of growth retardation and mimics hypopituitarism. The mechanisms by which sensory and emotional deprivation interferes with growth are not fully understood. Functional hypopituitarism is indicated by low levels of IGF-1 and by inadequate responses of GH to provocative stimuli. Puberty may be normal or even premature in its appearance. Appropriate history and careful observations reveal disturbed mother-child or family relations and provide clues to the diagnosis. Proof may be difficult to establish because the parents or caregivers often hide the true family situation from professionals, and the children rarely divulge their plight. Emotionally deprived children frequently have perverted or voracious appetites, enuresis, encopresis, insomnia, crying spasms, and sudden tantrums. The subgroup of children with hyperphagia and a normal body mass index tends to show catch-up growth when placed in a less stressful environment. Even when GH secretion is reduced, treatment with GH is not usually of benefit until the psychosocial situation is improved. Skeletal Dysplasia Skeletal dysplasias are heritable disorders of connective tissues of more than 300 disorders frequently associated with profound short stature and orthopedic complications. Although each skeletal dysplasia is relatively rare, collectively, the birth incidence of these disorders is almost 1 in 5000. These disorders are diagnosed based on radiographic, Blueprint in Pediatric Endocrinology 211

morphologic, clinical, and molecular criteria. The commonest examples are children with achondroplasia, hypochondroplasia and osteogenesis imperfecta. Most individuals with disproportionate short stature have skeletal dysplasias, and individuals with proportionate short stature have endocrine, nutritional, or prenatal-onset growth deficiency, or other non skeletal dysplasia disorders. There are exceptions to the rule, such as congenital hypothyroidism, which is usually, if not treated associated with disproportionate short stature, and disorders such as osteogenesis imperfecta (OI) and hypophosphatasia can be associated with normal body proportions. Anthropometric dimensions, such as upper-to-lower segment ratio, sitting height, and arm span, must be measured when considering the possibility of a skeletal dysplasia and should be measured in centimeters. Sitting height is an accurate measurement of head and trunk length, but it requires special equipment for precise measurements. Upper-to-lower segment ratio is easy to obtain and provide an accurate measurement of proportion. The lower segment is measured from the symphysis pubis to the floor at the inside of the heel. The upper segment is measured by subtracting the lower segment measurement from the total height. There are standards for upper-to-lower segment ratio. A child 8 to 10 years old has an upper-to-lower segment ratio of approximately 1 and as an adult has an upper-to-lower segment ratio of 0.95. An individual with short limbs and normal trunk has an increased upper to lower segment ratio, and an individual with normal limbs but short trunk has a diminished upper-to-lower segment ratio. Another means of determining if there is disproportion is based on arm span measurements, which are very close to total height in an average- proportioned individual. A short-limbed individual has an arm span considerably shorter than the height. Spinal disorders can lead to disproportionate short statue including irradiation to the spine, congenital spinal deformities (hemivertebrae, scoliosis, and kyphosis), skeletal dysplasia affecting the spine (Spondyloepiphyseal dysplasia) and others. 212 Chapter 6: Growth and Growth Disorders

Fig. (6-1): Showing Photo of a Child of Hypochondroplasia. SHOX Deficiency Syndromes The pseudoautosomal region of distal Xp and Yp (region escaping inactivation) includes a gene known as SHOX (short stature homeobox- containing gene), mutations of which are associated with syndromes of poor growth and skeletal dysplasia,such as Leri-Weil dyschondrosteosis, Turner Syndrome, and Langer's mesomelic dwarfism. The SHOX protein may affect cellular proliferation and apoptosis of chondrocytes in the growth plate. The auxologic finding of relatively short limbs suggests this gene defect which has been found in about 2% of children with so- called idiopathic short stature. This finding eliminates the ―idiopathic‖ and stresses the need for careful physical assessment. Skeletal dysplasias . 456 different conditions categorized in 40 different groups. . 316 conditions associated with different gene defects. . Achondroplasia and hypochondroplasia associated with mutation in FGFR3 gene. . Leri-Weill dyschondrosteosis associated with mutation in SHOX gene. Blueprint in Pediatric Endocrinology 213

. Achondroplasia / Hypochondroplasia. o Most common form of short limb form of short limb dwarfism in human. o Characterized by disproportionate short stature and Rhizomelia, frontal bossing, midfacial hypoplasia, low nasal bridge, exaggerated lumbar lordosis, brachydactylyl. o Autosomal dominanat with complete penetrance. . Hypochondroplasia is usually same clinical features but milder forms. o DNA – based testing is available about 70 % of affected indivisuals for a mutation in the FGFR3 gene. . Leri-Weill dyschondrosteosis (LWD). o Autosomal dominant inherited skeletal dysplasia. o Disproportionate short stature. o Mesomelic limb shortening. o Associated with mutation in SHOX gene. o Madelung deformity of the form arm. o More sevre in females, usually not clinical apparent till adolescence. o Bowing of the radius. o Dorsal dislocation of the ulna. o Premature fusion of the epiphysis. Chronic illness Any chronic medical condition can lead to short stature with or without poor weight gain and failure to thrive. Common conditions including, chronic heart disease (congenital or acquired), bronchial asthma (moderate or severe), cystic fibrosis celiac disease, inflammatory bowel disease (Crohn's disease and ulcerative colitis), juvenile idiopathic arthritis, chronic renal failure, renal tubular acidosis and poorly controlled diabetes mellitus. 214 Chapter 6: Growth and Growth Disorders

Heriditary Rickets Mainly hypophosphatemic and other inherited rickets which are usually severe rickets results in bone deformities and short stature which is usually disproportionate. In hypophosphatemic rickets, affected children appear to have a chronic renal phosphate leak with an appropriate response to hypophosphatemia. Hypophosphatemia leads to stimulation of renal 1α-hydroxylase causing increased synthesis and serum levels of calcitriol. As a result, intestinal absorption of calcium is enhanced, resulting in increased urinary excretion. Other characteristic features include rickets, short stature, normal serum calcium levels, and suppressed parathyroid function. Malnutrition Given the worldwide presence of under nutrition, it is not surprising that inadequate caloric and/or protein intake is the most common cause of growth failure in the developing world. Decreased weight gain generally precedes the failure of linear growth by a very short time in the neonatal period and by several years at older ages. Stunting of growth due to caloric and/or protein malnutrition in early life will often have lifelong consequences. Both acute and chronic malnutrition affects the GH-IGF system. The impaired growth is usually associated with elevated basal and/or stimulated serum GH levels; serum IGF-1 levels are reduced. Malnutrition may, consequently, be considered a form of GH insensitivity, with serum IGF-1 levels reduced despite normal or elevated GH levels. GHBP levels, as a reflection of GH receptor content, are decreased. Malabsorption / Gastrointestinal Diseases Growth retardation may predate other manifestations of malabsorption and/or chronic inflammatory bowel disease. Celiac disease (gluten-induced enteropathy) and regional enteritis (Crohn's disease) should be considered in the differential diagnosis of unexplained growth failure. Serum levels of IGF-1 may be reduced reflecting the malnutrition, and it is critical to discriminate between these conditions and GHD or related disorders causing IGF-1 deficiency. Blueprint in Pediatric Endocrinology 215

Syndromes & Short Stature Turner's syndrome

Fig. (6-2): Showing Clinical Features of Turner's syndrome. Most fetuses with Turner's syndrome spontaneously abort, but the incidence in live births is approximately 1 in 2500. Classically, the karyotype is 45, XO, but many patients retain an abnormal second X chromosome or even a fragment of a Y chromosome lacking SRY. Other patients are mosaic for 46, XX and 45, X cells and may have relatively mild phenotypes. Untreated patients are short. Many have typical dysmorphic features including lymphedema of the neck at birth, webbed neck, low posterior hairline, increased carrying angle of the arms, and shield chest with widely spaced nipples, low-set ears, and micrognathia. Patients typically have primary amenorrhea and are infertile, but occasionally they can have menarche followed by premature ovarian failure.

216 Chapter 6: Growth and Growth Disorders

Noonan's Syndrome Although this condition shares certain phenotypic features with Turner's syndrome, the two disorders are clearly distinct. In Noonan's syndrome, the sex chromosomes are normal, and transmission is apparently autosomal dominant, although about 50% of cases are sporadic. Both males and females may be affected, explaining the misleading terms ―Turner-like syndrome‖ and ―male Turner syndrome.‖ Affected individuals typically have webbing of the neck, a low posterior hairline, ptosis, cubitus valgus, and malformed ears. Cardiac abnormalities are primarily right-sided (pulmonary valve, more frequently in the mutation positive patients), rather than the left-sided lesions (aorta, aortic valve) characteristic of Turner's syndrome. Microphallus and cryptorchidism are common, and puberty may be delayed or incomplete. Mental retardation of variable degrees is present in approximately 25% to 50% of patients.

Fig. (6-3): Showing Clinical Features of Noonan's Syndrome. Russell-Silver Syndrome Common findings include antenatal and postnatal growth failure, congenital hemi hypertrophy, and small, triangular facies. Nonspecific findings include clinodactyly, precocious puberty, delayed closure of the Blueprint in Pediatric Endocrinology 217

fontanels, and delayed bone age. Adults are short with final heights around - 4 SD below the mean. Endogenous GH secretion in prepubertal is similar to that in other short IUGR and less than in AGA short children. Inheritance is usually sporadic occurrence in majority of cases. Almost 19% of cases with more than one affected individuals in the family, providing evidence for a genetic cause as the following: . Autosomal recessive (17.4%). . Autosomal dominant (8.7%). . X-linked dominant (74%). . Russell-Silver Syndrome is often used incorrectly as a designation for IUGR of unknown etiology

Fig. (6-4): showing clinical features of Russell-Silver Syndrome Seckel's Syndrome (Seckel's Bird Headed Dwarfism) Is an autosomal recessive called as "bird-headed dwarfism,‖ developmental disorder characterized by disorder of IUGR and severe postnatal growth failure, combined with microcephaly, a hypoplastic face with a prominent nose, low-set and/or malformed ears and micrognathia. Approximately 25% of patients have aplastic anemia or malignancies. One locus for the syndrome maps to 3q22.1–q24. A second locus maps to 18p11.31–q11.2, demonstrating genetic heterogeneity. Final height is typically 90 to 110 cm, with moderate to severe mental retardation. 218 Chapter 6: Growth and Growth Disorders

Fig.(6-5): Child With Seckle Syndrome Down syndrome (Trisomy 21) Down syndrome is a chromosomal condition characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (Trisomy 21) or part (such as due to translocations). The incidence of Down syndrome is estimated at 1 per 800 births. Physical features include, microcephaly, flattening of occiput and face, upward slant to eyes with epicanthal folds, brush field spots in iris, broad, stocky neck, small feet, hands, digits, single palmer crease, hypotonia, short stature, associated with congenital heart disease, malformations of the GI tract, cataracts, hypothyroidism, hip dysplasia, obstructive sleep apnea, and myeloproliferative disorders. About half of children with Down syndrome are born with congenital heart disease, with the most common lesions being atrial septal defect and ventricular septal defect. Persistent primary congenital hypothyroidism is found in 1 in 141 newborns with Down syndrome, as compared with 1 in 2500 in the general population. Ophthalmologic disorders increase in frequency with age; >80% of children aged 5 to 12 years have disorders that need monitoring or intervention, such as refractive errors, strabismus, or cataracts, renal and urinary tract abnormalities. Individuals with Down syndrome have a wide range of function, but all will have decrease in intelligence quotient (IQ) in first decade of life. This syndrome accounts for approximately one third of moderate-to-severe cases of mental retardation. Deficiency of language production relative to other areas of development often causes substantial impairment. Blueprint in Pediatric Endocrinology 219

Fig. (6-6): Showing Clinical Features of Down's syndrome. Prader-Willi Syndrome Rare genetic disorder in which seven genes on chromosome 15 (q 11-13) are deleted or unexpressed (15q partial deletion) on the paternal chromosome. It was first described in 1956 by Andrea Prader. The incidence of PWS is between 1 in 25,000 and 1 in 10,000 live births. The probable cause of the short stature in PWS is deficient GH production due to as yet undefined hypothalamic dysfunction. The body habitus and composition are similar to classic GHD, including small hands and feet, increased fat mass and low muscle mass and bone mineral density. Low mean serum GH levels or inadequate responses after provocative testing may reflect the impact of obesity, but serum levels of GH-dependent peptides are low in PWS, in contrast to the findings in exogenous obesity where these factors are produced normally despite diminished GH production. 220 Chapter 6: Growth and Growth Disorders

Fig. (6-7): Showing Child with Prader-Willi Syndrome. DiGeorge Syndrome DiGorge syndrome is caused by the deletion of a small piece of chromosome 22.It has a prevalence estimated at 1:4000.The syndrome was described in 1968 by the pediatric endocrinologist "Angelo DiGeorge". Characteristic signs and symptoms may include birth defects such as congenital heart disease, defects in the palate, most commonly related to neuromuscular problems with closure (velo-pharyngeal insufficiency), learning disabilities, mild differences in facial features, and recurrent infections. Infections are common in children due to problems with the immune system's T-cell mediated response that in some patients is due to an absent or hypoplastic thymus. 22q11.2 deletion it may be first spotted when an affected newborn has heart defects or convulsions from hypocalcaemia due to malfunctioning parathyroid glands and low levels of parathyroid hormone. Affected individuals may also have any other kind of birth defect including kidney abnormalities Blueprint in Pediatric Endocrinology 221

and significant feeding difficulties as babies. Autoimmune disorders such as hypothyroidism and hypoparathyroidism or thrombocytopenia (low platelet levels), and psychiatric illnesses are common late-occurring features.

Fig. (6-8): Child with DiGeorge Syndrome.

Growth Hormone Deficiency (GHD) The frequency of GH deficiency (GHD) has been estimated in various studies to range from 1:4000 to 1:10,000. Human GH is a 191- amino-acid single-chain polypeptide that is synthesized, stored, and secreted by somatotrophs in the pituitary. Its gene (GH1) is located on the long arm of chromosome 17 (q22–24). GH is secreted in a pulsatile fashion under the regulation of hypothalamic hormones. The alternating secretion of growth hormone–releasing hormone (GHRH), which stimulates GH release, and somatostatin, which inhibits GH release, accounts for the rhythmic secretion of GH. Ghrelin, a peptide produced in the arcuate nucleus of the hypothalamus and in much greater quantities by the stomach, also stimulates GH secretion. Physiologic factors also have a role in the stimulation and inhibition of GH. Sleep, exercise, physical stress, trauma, acute illness, puberty, fasting, and hypoglycemia stimulate the release of GH, whereas hyperglycemia, hypothyroidism, and glucocorticoid inhibit GH release. The biologic effects of GH include increases in linear growth, bone thickness, soft tissue growth, and protein synthesis, fatty acid release 222 Chapter 6: Growth and Growth Disorders

from adipose tissue, insulin resistance, and blood glucose levels. The mitogenic actions of GH are mediated through increases in the synthesis of insulin-like growth factor-1, formerly named somatomedin C, a 70- amino-acid single-chain peptide coded for by a gene on the long arm of chromosome 12. IGF-1 has considerable homology to insulin. Circulating IGF-1 is synthesized primarily in the liver and formed locally in mesodermal and ectodermal cells, particularly in the growth plate of children, where its effect is exerted by paracrine or autocrine mechanisms. Circulating levels of IGF-1 are related to blood levels of GH and to nutritional status. IGF-1 circulates bound to several different binding proteins. The major one is a 150-kd complex (IGF-BP3), which is decreased in GH-deficient children. Human recombinant IGF-1 may have therapeutic potential in conditions characterized by end organ resistance to GH such as Laron syndrome and the development of antibodies to administered GH. IGF-2 is a 67-amino-acid single-chain protein that is coded for by a gene on the short arm of chromosome 11. It has homology to IGF-1. Less is known about its physiologic role, but it appears to be an important mitogen in bone cells, where it occurs in a concentration many times higher than that of IGF-1. GHD can present as an isolated pituitary deficiency or can be associated with other pituitary hormone deficiencies, been the most common being TSH deficiency and less common gonadotropin or ACTH deficiencies. During early childhood isolated GHD can present with a classical phenotype of growth failure, protrusion of the frontal bones and poor development of the bridge of the nose. Closure of the anterior fontanel may be delayed and dental eruption and skeletal maturation are usually quite delayed. The penis is often small and this may be accentuated by the presence of truncal obesity. Delay of puberty is frequent. However if gonadotropin function is intact, puberty will develop. Blueprint in Pediatric Endocrinology 223

Congenital GH Deficiency

Fig. (6-9): Showing Child with Congenital GH Deficiency. Hypothalamic–Pituitary Malformations Anterior and posterior pituitary deficiencies associated with various congenital syndromes affecting the hypothalamus, the pituitary, or both may be discovered through magnetic resonance imaging (MRI) of the hypothalamus and pituitary gland. These abnormalities may result in apparent deficiencies in infancy or not until later in childhood. Anencephaly has long been recognized as a cause of an ectopic, hypoplastic, or malformed pituitary gland. Slightly less severe in the clinical spectrum of major cranial malformations, holoprosencephaly is commonly associated with hypothalamic defects resulting in pituitary hormone deficiency. Associated defects can range from cyclopia to hypertelorism, with varying coexistent defects, including palatal or lip clefts, nasal septal aplasia, or, in surviving older children, a single central incisor. Schizencephaly, sometimes identified by MRI during evaluation of gait disturbance, can also be associated with hypothalamic–pituitary malformation. Lastly, even isolated cleft lip or palate may be associated with hypothalamic or pituitary defects. Septo-optic dysplasia (SOD) is another malformation syndrome closely associated with hypopituitarism. At least 50% of children with SOD have hypopituitarism. A child identified as having SOD should be referred to a pediatric endocrinologist for monitoring or testing. In its most severe form, SOD is associated with hypoplasia or absence of the optic nerves or chiasm, agenesis or hypoplasia of the septum pellucidum, and hypothalamic defects, and is known as deMorsier syndrome. Typically, growth failure 224 Chapter 6: Growth and Growth Disorders

due to GH deficiency becomes apparent between 6 and 18 months of age. Other specific, rare genetic syndromes can be associated with hypopituitarism. Rieger‘s syndrome, the result of a transcription factor gene mutation, results in hypopituitarism associated with coloboma of the iris, glaucoma, and dental hypoplasia. Pallister Hall syndrome is associated with hypothalamic hamartomablastoma, micropenis, cryptorchidism, and postaxial polydactyly. Because MRI is used increasingly in the evaluation of children with unexplained neurological findings, additional genetic syndromes affecting the structural integrity of the hypothalamic–pituitary axis may be recognized. The use of MRI has led to the recognition that many children thought to have idiopathic GH deficiency actually have abnormal posterior pituitary or stalk regions. Hereditary GH Deficiency Numerous mutations have been described, however, affecting homeodomain transcription factors for pituitary development, the GHRH receptor, and GH genes. Gene defects of the GH-1 gene appear to result in four variants of hereditary GH deficiency. Approximately, 3-30% of patients with isolated GHD had been reported to have an affected parent, sibling or child. Familial isolated GHD is associated with at least four Mendelian disorders. These include two forms that have autosomal recessive inheritance as well as autosomal dominant and X-linked forms: . Type IA (recessive, absent GH, antibodies to hGH therapy; severe clinical phenotype) . Type IB (recessive, low GH, response to hGH therapy; clinical features include height SDS - 2) . Type II (dominant, low GH, response to hGH therapy; patients diagnosed with Type II have one affected parent and vary in clinical severity between kindred`). . Type III (X-linked, low GH, response to hGH therapy; Clinical findings differ in different families. Affected individuals have agammaglobulinemia associated with their IGHD but others do not). The most severe form of isolated GHD is Type IA. Initially, all individuals with Type IA were found to be homozygous for GH1 gene deletions and they developed anti-GH antibodies with treatment. Blueprint in Pediatric Endocrinology 225

However, additional cases with complete GHD owing to GH1 gene deletions have been described who respond well to GH treatment. Autosomal dominant IGHD is also caused by mutations in GH1. The mutations usually involve splice site errors in intron 3. Additional deficiencies of TSH and / or ACTH have been recognized as late complications in patients with dominant mutations in GH1. Two loci on the X chromosome have been associated with hypopituitarism. The first lies at Xq21.3-q22. Mutations in this region produce hypogammaglobulinemia as well as IGHD. The second locus maps farther out on the long arm, at Xq24-q27.1, a region containing the SOX2 transcription factor gene. Abnormalities in this locus have been linked to IGHD with mental retardation as well as to MPHD with the triad of pituitary hypoplasia, missing pituitary stalk, and ectopic posterior pituitary gland. GH1 Gene GH1 gene is one of a cluster of 5 genes on chromosome 17q22–24. This cluster arose through successive duplications of an ancestral GH gene. Recessively transmitted mutations in the GH1 gene produce a similar phenotype. Missense, nonsense, and frame shift mutations are described. The most common involve the 4th and final intron of the gene. These mutations eliminate the normal splice donor site and foster use of an alternative site. The abnormal mRNA encodes a protein that is longer than normal and has no biologic activity. GHRH Receptor A recessive loss-of-function mutation in the receptor for GHRH interferes with proliferation of somatotrophs during pituitary development and disrupts the most important signals for release of GH. The anterior pituitary is small, in keeping with the observation that somatotrophs normally account for greater than 50% of pituitary volume. There is reduction of fetal growth, followed by severe postnatal growth failure. Congenital Structural CNS defects Hypopituitarism as well as anomalous presentation of the pituitary or the pituitary stalk can result from a congenital mid-line malformation. Based on MRI studies these malformations have been divided into 226 Chapter 6: Growth and Growth Disorders

hypoplasia or aplasia, ectopic localization and agenesis or pituitary stalk- section. These patients will present in addition to the presence of midline defects with symptoms and signs such as those described for congenital hypopituitarism. Septo-optic dysplasia (deMorsier Syndrome), the combination of optic nerve defects and agenesis of the septum pellucidum, has been known for more than 50 years and it is known that these abnormalities are associated with hypopituitarism. However, most septo-optic dysplasia occurs sporadically and recent studies of patients with mild forms of pituitary hypoplasia have shown a genetic basis, resulting from a heterozygous mutation of the HESX1 gene. Acquired GH Deficiency Perinatal pathology (prenatal infections, trauma, hypoxia). GHD associated with congenital rubella, toxoplasmosis and cytomegalovirus infections have been described. Perinatal trauma especially associated with forceps delivery, vaginal bleeding and breech presentations. CNS Tumors Craniopharnygioma It is the most common tumor in the hypothalamic-pituitary region to cause pituitary deficiency in childhood. The tumor usually arises from remnants of Rathke's pouch, an invagination of the epithelium within the third pharyngeal pouch from which the anterior pituitary evolves. Although histologically a benign tumor, it is locally invasive, involving adjacent structures especially the optic tracts and base of the third ventricle. It usually has a solid and cystic component that may contain a cholesterol-rich fluid. The clinical presentation is usually characterized with signs and symptoms of increased intracranial pressure and visual disturbances due to the proximity of the optic chiasm. Visual field defects are common and include homonymous hemianopia, bitemporal hemianopia, decreased visual acuity and optic atrophy. GH deficiency (72%) is the most common endocrine abnormality at clinical presentation, whereas ACTH, TSH and ADH deficiencies were found in approximately 25% of cases. The management of craniopharyngioma is complex, still controversial, and morbidity remains high. The choice of treatment varies from centre to centre including surgery with total removal; surgery with partial removal; irradiation; installation of radioactive substances to the cystic component or a combination of these Blueprint in Pediatric Endocrinology 227

treatment modalities. Following surgery endocrine deficiencies of ADH, ACTH, TSH, GH, LH and FSH are highly likely, therefore these patients should be carefully monitored and appropriate hormonal replacement therapies commence promptly. It is important to mention that many children who have been surgically treated for craniopharyngioma may continue to grow with a normal growth velocity despite having clearly documented low GH and low IGF-1. Hyperinsulinism associated with hyperphagia and the marked weight gain observed in these children may explain their normal growth velocity. . Germinoma and optic nerve glioma: These tumors usually involve the hypothalamic-pituitary axis. Glioma or astrocytoma usually present with increased intracranial pressure whereas germinoma may present with anorexia and weight loss in older boys and with diabetes insipidus alone. Idiopathic diabetes insipidus must always be investigated with regular CNS imaging. Pituitary stalk thickening may be the first radiological abnormality. Elevation of serum and possibly cerebrospinal fluid human chorionic gonadotropin (hCG) levels can be used as a tumor marker. . Optic nerve glioma, which occurs more commonly in patients with neurofibromatosis, may also be associated with pituitary deficiency. These tumors can be treated with targeted radiotherapy, which may also cause pituitary deficiency. . Histiocytosis typically involves the hypothalamus and causes diabetes insipidus. Tumors are usually seen in the pituitary stalk and lesions may resolve with chemotherapy. In approximately 30% of cases this will be associated with anterior pituitary deficiencies. Cranial Irradiation All children who have received CNS irradiation, whether for prophylaxis for leukemia, for tumors distant from or adjacent to the hypothalamic-pituitary region or during total body irradiation, are at some risk for the development of GHD. The sensitivity of the hypothalamic-pituitary axis to irradiation is dependent on the total dose, fractionation of irradiation, tissue localization and the age of the patient. Children who receive radiotherapy for CNS tumors or prevention of CNS malignancies (leukemia) are at risk for developing GH deficiency. Spinal irradiation contributes to disproportionately poor growth of the trunk 228 Chapter 6: Growth and Growth Disorders

independent of GH status. Growth typically slows during radiation therapy or chemotherapy, improves for 1–2 years, and then declines with the development of GH deficiency. The dose and frequency of radiotherapy are important determinants of hypopituitarism. GH deficiency is almost universal 5 years after therapy with a total dose ≥35 Gy. More subtle defects are seen with doses around 20 Gy. Deficiency of GH is the most common defect, but deficiencies of TSH and ACTH may also occur. Unlike in other forms of hypopituitarism, puberty tends to be early rather than delayed. The clinician is likely to encounter children in the 8- to 10-yr age range who are growing at rates that are normal for chronological age but subnormal for stage of pubertal development. Diagnostic approach to the child with short stature A graded diagnostic approach, with a careful history, physical examination, and targeted laboratory and radiological evaluation is recommended in order to determine the etiology and guide treatment. The first evaluation may not yield the diagnosis, and careful follow-up over months or even years is sometimes required. History A thorough history is important in establishing the cause of a child's short stature. Birth weight, length, and gestation will identify whether the child was born small for gestational age. Perinatal complications, such as hypoglycemia or micropenis, are suggestive of growth hormone deficiency. Medical history include, dyspnoea may suggest a cardiac or pulmonary cause, such as moderate / severe asthma, or chronic heart disease. Diarrhea may suggest celiac disease or other malabsorption syndromes. Blood in stools may indicate inflammatory bowel disease. Joint pains and rash may indicate a systemic inflammatory condition such as juvenile idiopathic arthritis. Recurrent respiratory infections with diarrhea may raise suspicion of cystic fibrosis. Other symptoms include nasal polyps, delayed puberty, and failure to thrive. Patient may have diabetes with symptoms of polyuria, polydipsia, and weight loss. There may be a history of headache or diplopia, suggestive of a craniopharyngioma with other pituitary hormone dysfunction, or there may be a history of recent brain surgery. The child may be a long-term survivor of other malignancies such as acute lymphoblastic leukemia, having received chemotherapy or radiotherapy. Radiotherapy to the spine Blueprint in Pediatric Endocrinology 229

results in disproportionate short stature. Recent weight gain, acne, mood swings, and headaches may be present with Cushing's syndrome. Fatigue, cold intolerance, dry skin, hair loss, constipation, lethargy, and weight gain suggest hypothyroidism. Presence of multiple systemic congenital abnormalities (e.g., Turner's syndrome, Trisomy 21, DiGeorge syndrome) may raise suspicion of syndromic short stature. History of psychological abnormalities, bingeing, purging, and altered body image suggests anorexia nervosa or bulimia nervosa. Family history includes, parental heights and calculation of the target height, and weights and heights of siblings, should be undertaken. A history of either parent being a 'late bloomer' or of parental consanguinity should also be obtained. Social history should ascertain family dynamics and raise any suspicion of neglect, abuse, or starvation. Parent-child bonding and interaction should be observed. Dietary history include adequate caloric intake and access to food should be ensured. Medication history include chronic corticosteroid treatment may lead to iatrogenic short stature. History such as treatment for attention deficit-hyperactivity disorder should be obtained. Developmental history include, delayed development in syndromic short stature such as Prader-Willi syndrome, DiGeorge syndrome, Trisomy 21, and psychosocial deprivation. Examination Accurate measurements, using correct age and sex-specific growth charts, are mandatory to make sure that the child is in fact short. Care must be taken to plot the height and weight based on the child's actual chronological age. Length should be measured supine in infants until 2 years of age, and standing thereafter. Height should ideally be measured with a wall-mounted stadiometer while making sure that the child is shoeless, standing up straight, and not leaning on the wall, with his/her feet together and looking directly forwards. Infant length should be measured from crown of head to outstretched heel on a firm platform with a fixed headplate and a moveable footplate. Growth Velocity Growth velocity determines the change in height over time. It is calculated as the difference in height on 2 different occasions annualized over a year. Growth velocities depend on age and pubertal status. Height that plots stably along a given percentile on the growth chart reflects 230 Chapter 6: Growth and Growth Disorders

normal growth velocity. Crossing percentiles in the downward or upward directions reflects abnormally low or accelerated growth velocities, respectively. A complete review of systems needs to be undertaken in order to help exclude an undiagnosed syndrome or chronic medical condition. Dysmorphic features are very important to look for them. Tachycardia may indicate cardiac failure; bradycardia may suggest eating disorders or severe hypothyroidism. Tachypnoea may be observed in respiratory disorders such as cystic fibrosis or other chronic cardiac and pulmonary diseases. Pallor may indicate anemia due to chronic illnesses, malabsorption syndromes, or malignancies. Hypothermia may be observed in chronic hypothyroidism. Hypertension is present in Cushing's syndrome. Pallor, dry skin, facial coarsening, hair loss, with a non-pitting edema suggest hypothyroidism. Lymphedema is observed with Turner's syndrome. Increased weight, cushingoid features (buffalo hump, hirsutism, violaceous striae) are present in Cushing's syndrome; looking much younger than stated age with a low muscle-to-fat ratio suggests GH deficiency. Midline defects such as a single incisor or cleft palate may be found with congenital GH deficiency. Blue sclera and fractures are present in osteogenesis imperfecta. Characteristic bony deformities such as rachitic rosary or genu varum suggest rickets. Milk bottle caries, poor hygiene, or severe diaper rash suggest neglect; bruising in preambulatory infants or patterned bruising in older children suggest abuse, as do inadequately explained injuries; retinal hemorrhages may be present if the child has been shaken violently. Disproportionate short stature with shortening of the distal or proximal sections of upper or lower extremities is indicative of skeletal dysplasia; additional skeletal deformities may be present; kyphoscoliosis or other spinal deformities are evident in children with achondroplasia, or there may be evidence of spinal surgeries. Muscle wasting, anemia, and other signs of malnutrition suggest malabsorption, anorexia nervosa, bulimia nervosa, starvation, child abuse, neglect, or chronic severe medical conditions. Joint swellings, rash, murmur is present in juvenile idiopathic arthritis. A murmur suggests congenital heart disease, isolated or associated with genetic syndromes. Signs of pneumonia may be present in cystic fibrosis and other respiratory conditions. Abdominal distension suggests celiac disease and other malnutrition states. Abnormal neurology may be present with CNS tumors. Blueprint in Pediatric Endocrinology 231

Pubertal status needs to be carefully assessed because it indicates skeletal maturation and growth potential. Pubertal delay points to a possibility of constitutional delay of growth and development, or hypogonadotrophic hypogonadism due to hypopituitarism. Any patient who falls below the third percentile in height and /or has decreased growth rates (falling across the major percentiles) should receive a complete diagnostic evaluation. It is important to assess, growth velocities, history of chronic illness and medications, midparental and target height, birth size, growth pattern, nutritional state, pubertal stage, body segment proportions, bone age, and predicted adult height. There are many causes of growth disorders. Systemic conditions such as inflammatory bowel disease, celiac disease, occult renal disease, and anemia must be considered. Patients with systemic conditions often have greater loss of weight than length. A few otherwise normal children are short (> 3 SD below the mean for age) and grow 5 cm/year or less but have normal levels of GH in response to provocative tests and normal spontaneous episodic secretion. Most of these children show increased rates of growth when treated with GH in doses comparable to those used to treat children with hypopituitarism. Plasma levels of IGF-1 in these patients may be normal or low. Several groups of treated children have achieved final or near final adult heights. Different studies have found changes in adult height that range from −2.5 to +7.5 cm compared with pretreatment predictions. No methods can reliably predict which of these children will become taller as adults as a result of GH treatment and which will have compromised adult height. Diagnostic strategies for distinguishing between permanent GH deficiency and other causes of impaired growth are imperfect. Children with a combination of genetic short stature and constitutional delay of growth have short stature, below average growth rates, and delayed bone ages. Many of these children exhibit minimal GH secretory responses to provocative stimuli. When children who have been diagnosed with idiopathic or acquired GH deficiency are treated with hGH and are retested as adults, the majority have peak GH levels within the normal range. Initial Investigations . Complete blood count looking for anemia 232 Chapter 6: Growth and Growth Disorders

. Complete metabolic profile (electrolyte abnormalities in renal and other chronic diseases) including looking for metabolic acidosis, and for hypocalcaemia (e.g., in DiGeorge syndrome, rickets). . ESR to rule out underlying undiagnosed chronic inflammatory illness . IgA Tissue transglutaminase antibodies to screen celiac disease (be sure that, total IgA level is normal to avoid false negative celiac antibodies screening). . Urine analysis to rule out infection, a or proteinuria (with chronic renal disease), and to detect renal tubular acidosis . TSH and fT4 to screen for hypothyroidism even if there is no other symptoms of hypothyroidism apart from short stature . Insulin-like growth factor 1 and IGF-binding protein 3 to screen for GH deficiency. Values below -2 SDS, corrected for age and sex, are indicative of GHD; however, normal concentrations do not rule out GHD. The concentrations can also be altered in hypothyroidism, malnutrition, and chronic diseases. IGF-1 and IGFBP levels are decreased in growth hormone deficiency and may help in differentiating short children with growth hormone deficiency. However, these tests are not useful in nutritional growth retardation or younger patients. Measuring levels of GHBP or IGFBP may also help differentiate the different conditions, as well as IGF levels and their response to exogenous growth hormone administration. . A karyotype is imperative in every girl with short stature, even in the absence of the stigmata of Turner syndrome. . Bone age is very important and the most commonly used method is "Greulich and Pyle", which examines the left wrist and hand, but other methods such as knee examination may be more helpful in infants. Bone age may also be used to predict final height using the tables of Bayley and Pinneau. . Children who demonstrate skeletal abnormalities on physical examination deserve evaluation for metabolic bone disease, such as mucopolysaccharidosis, mucolipidosis, and gangliosidosis. In addition, skeletal survey abnormalities should be looked for in accordance with Blueprint in Pediatric Endocrinology 233

body proportion alterations detected on physical examination s (e.g. hypochondroplasia, osteogenesis imperfecta, Achondroplasia). . Vitamin D metabolites to screen for rickets. Specific Tests GH Stimulation Tests Due to pulsatile secretion GH levels are often low during much of a 24h period.

. GHD cannot be diagnosed with a random blood sample for GH measurement.

The GH stimulation test was established to assess the maximum serum GH concentration that can be released in response to a pharmacological stimulus. There are many pharmacological agents will induce GH release and some of them will also stimulate ACTH secretion causing an increase in serum cortisol. There is an extensive literature on the relative advantages and disadvantages of the different GH stimulation tests. The insulin-tolerance test (ITT) is less used in the pediatric endocrine services because of the risk of serious hypoglycemia, although in experienced units the ITT is safe. This test probably provides the best- validated stimulus for GH secretion. However, it should not be performed in children under 5 years of age. The GH-IGF1 axis can be stimulated with various provocative agents such as insulin, glucagon, L- arginine, L-Dopa, GHRH, and clonidine. Various cut-offs have been used, but GHD is generally defined as a value of less than 10 microgram / l on 2 pharamacological stimuli. GH provocation tests are contraindicated in children aged less than 1 year. Remember that random GH sample is useless and has no value in the diagnosis of GH deficiency as GH secretion is pulsatile. There is no agreement regarding the need to prime prepubertal children with sex steroids before testing, although it is preferable. Hypothyroidism must be excluded before GH testing. GH Markers The clinical usefulness of measuring markers of growth hormone (GH) action such as IGF-1, IGFBP-3 and ALS in patients with disorders 234 Chapter 6: Growth and Growth Disorders

of GH secretion has been widely reported. The clinical value of single measurements of IGF-1, IGFBP-3, and ALS, alone or in combination, in children with GHD have proven to be useful biochemical tools in confirming the clinical diagnosis. Other Possible Diagnostic Tests According to The Clinical Suspicions for Example: . Molecular investigations of the GH gene and of other candidate genes should be considered in children with familial GHD or in children with sporadic forms of classical GHD, in particular in children with multiple pituitary hormone deficiency. . Diurnal cortisol levels, urinary cortisol levels and a dexamethasone suppression test for suspected Cushing's syndrome. . IGF-1 generation test in patients with a high basal GH and suspected to have GH insensitivity. . Echocardiogram for congenital heart diseases. . Genetic evaluation with karyotype for other genetic syndromes. . Appropriate investigations for chronic illnesses such as a sweat test for cystic fibrosis, rheumatoid factor in juvenile idiopathic arthritis, HbA1C in diabetes mellitus, endoscopy in inflammatory bowel disease and a referral to the appropriate specialist if underlying undiagnosed medical condition identified. Indications of GH Testing in Children . History of cranial irradiation, or head trauma or past histories of central nervous system infections associated with short stature . Past history of birth asphexia . Consanguinity and/or an affected family member with GH deficiency . Craniofacial midline abnormalities . Severe short stature (less than− 3 SDS) . Height less than - 2 SD and a height velocity over 1 year less than - 1 SDS . Signs indicative of an intracranial lesion . Signs of multiple pituitary hormone deficiency (MPHD) Blueprint in Pediatric Endocrinology 235

Radiological Investigations . MRI of the brain helps identify congenital abnormalities of the forebrain and pituitary, optic chiasm, and optic nerves. . MRI will detect acquired abnormalities such as a solid/cystic suprasellar mass extending into the hypothalamus and third ventricle (craniopharyngioma), optic glioma; Rathke's cleft cysts, and arachnoids cyst. Inflammatory lesions such as Langerhans cell histiocytosis will be revealed as thickening of the pituitary stalk. . CT of the brain and x-ray of the skull may help to detect bony abnormalities and intracranial calcification (craniopharyngioma). Genetic Testing in Short Children . As a rule, the diagnosis of genetic conditions are based on both clinical and laboratory findings. . Children with short stature and dysmorphic features may have their diagnosis confirmed by these genetic testing. . Exome / genome sequencing should be used more frequently for the diagnosis of genetically determined conditions. . Analysis of mutations in IGF1R in cases of Acondroplasia/ Hpochondroplasia . SHOX gene mutations in cases with Turner's syndrome, idiopathic short stature and in Leri-Weill dyschondrosteosis. . The identification of genetic defect has clearly implications for rhGH treatment and follow- up. Growth hormone therapy Human growth hormone (GH) was first used more than 30 years ago to stimulate growth in a child with hypopituitarism. Subsequently, a limited supply of pituitary glands from which GH could be extracted and purified required that GH therapy be restricted to children with the most severe and unequivocal GH deficiency. In 1985, seven cases of Creutzfeldt-Jakob disease (CJD) in patients who had received GH which were contaminated with subviral particles. It was fortunate that 192 amino-acid biosynthetic GH was approved by the Food and Drug Administration (FDA) in 1985 and a second 191 amino acid biosynthetic 236 Chapter 6: Growth and Growth Disorders

GH was approved in 1987. The production of GH by biological systems (Escherichia coli and, more recently, mammalian cells) transplanted with the GH gene yields a virtually unlimited supply of GH. Biosynthetic GH therapy eliminated the risk of CJD and offered children with severe GH deficiency an opportunity for optimal treatment. Children with milder forms of inadequate GH secretion, previously excluded from receiving GH, could be treated. Increased availability of recombinant DNA-derived GH has also allowed investigation of its growth-promoting effects in poorly growing children who do not fit traditional definitions of growth hormone deficiency (GHD), many of whom were previously believed to be unresponsive to GH treatment. In addition, metabolic effects of GH apart from linear growth promotion are now being studied extensively, leading to new indications for GH therapy. The Lawson Wilkins Pediatric Endocrine Society, Academy of Pediatrics, and GH Research Society all have published guidelines for hGH treatment. In children with classic GH deficiency, treatment should be started as soon as possible to narrow the gap in height between patients and their classmates during childhood and to have the greatest effect on mature height. In healthy children GH production is 20 microgram /kg /day, and physiologically rises to 35 microgram /kg /day in late puberty. The recommended dose of rhGH during childhood is 0.18–0.3 mg /kg /week or of 35-50 µg /kg /day (0.035-0.05 mg /kg /day), (multiply by factor 3 to convert the dose into international unit). Higher doses have been used during puberty which is controversial issues among endocrinologist, one group supports that as it mimics physiological rise, but second group not supporting that with increasing the dose, the bone age will be increasing and final height would be the same. Recombinant GH is administered subcutaneously in 6 or 7 divided doses. Maximal response to GH occurs in the first year of treatment is 8 - 14 cm; the response decline in second year of therapy for GH deficient children to 7- 11cm / year, with each successive year of treatment, the growth rate tends to decrease. Good response is best evaluated by calculating change in height SDS / year and should be more than 1 SDS / year, while poor response is defined by change in height SDS/ year less than 0.4 SDS, compliance should be evaluated before the dose is increased. Concurrent treatment with GH and GnRH agonist has been used in the hope that interruption of puberty will delay epiphyseal fusion and Blueprint in Pediatric Endocrinology 237

prolong growth. This strategy can increase adult height. It can also increase the discrepancy in physical maturity between GH-deficient children and their age peers and may impair bone mineralization. There have also been attempts to forestall epiphyseal fusion in boys by giving drugs that inhibit aromatase, the enzyme responsible for converting androgens to estrogens. Growth hormone therapy should be continued until near final height is achieved. Criteria for stopping treatment include a decision by the patient that he or she is tall enough, a growth rate less than 2 cm/year and a bone age >14 years in girls and >16 years in boys. Some patients develop either primary or central hypothyroidism while under treatment with GH. Similarly, there is a risk of developing adrenal insufficiency. If unrecognized, this can be fatal. Periodic evaluation of thyroid and adrenal function is indicated for all patients treated with GH. GH is currently approved for treatment of children with growth failure as a result of Turner's syndrome, end-stage renal failure before kidney transplantation, Prader-Willi syndrome, intrauterine growth retardation, and idiopathic short stature. In children with MPHD, replacement should also be directed at other hormonal deficiencies. In TSH deficient subjects, thyroid hormone is given in full replacement doses. In ACTH-deficient patients, the optimal dose of hydrocortisone should not exceed 10 mg /m2 /day. In patients with a deficiency of gonadotropin, gonadal steroids are given when bone age reaches the age at which puberty usually takes place. For infants with microphallus, one or two courses of monthly intramuscular injections of 25 mg of testosterone cypionate or testosterone enanthate (each course consists of three injections) may bring the penis to normal size without an inordinate effect on osseous maturation. Adverse Effects of GH Some patients treated with GH have developed leukemia but there was no proof that it was releated to growth hormone. The increased risk is attributable to children with additional risk factors such as cranial irradiation. Growth hormone treatment does not increase the risk for recurrence of brain tumors or leukemia. Other reported side effects include pseudotumor cerebri especially in obese children with GH deficiency, slipped capital femoral epiphysis, gynaecomastia, and worsening of scoliosis. There is an increase in total body water content during the first 2 weeks of treatment. Fasting and postprandial insulin 238 Chapter 6: Growth and Growth Disorders

levels are characteristically low before treatment, and they normalize during GH replacement. Treatment does not increase risk of type 1 diabetes, but it may increase the risk of type 2 diabetes. Finally, Bone pains most commonly encountred complaints. Monitoring of GH Therapy . In the first year, experts recommend to see the patient every 3 months, and in subsequent years every 6 months. . Determination of growth response (change in height SDS-score). . Monitoring of IGF-1 levels to evaluate safety and possibility for dose-titration. . Interval measurements of serum IGF-1 and IGFBP-3 levels (every 3 to 6 months) . Annual assessment of fasting glucose/insulin ratio and thyroid function tests. . Monitoring adherence is crucial and experts favour use of an injection recording device. IGF-1 levels can be useful, but are heavily influenced by recent GH injections. It is important to educate physicians, patients, and patient families on the importance of adherence. . Screening for potential adverse effects. . Consideration of dose adjustment based on IGF-1 values, growth response, and comparison to growth prediction models. Defining the Response to GH Treatment Response to GH treatment is highly variable and dependent on both, indication and its severity of growth hormone deficiency. Growth dose of 35-50 µg /kg / day (0.035-0.05 mg /kg /day), but plateaus after this point. It is also affected by genetics, age, adherence, and co-morbidities. The heterogeneity of response makes the definition of good and poor response difficult. GH therapy management is focused on poor responders, and a definition of poor response has more clinical value than a definition of good response. Short-term auxological features that suggest a successful first-year response to GH treatment in individual patients include a change in height SDS of more than 0.3–0.5, a first-year height velocity increment of more than 3 cm / year, or a height velocity Blueprint in Pediatric Endocrinology 239

SDS of more than +1. Restoration to a more normal height during childhood is an important consideration. Mathematical models can be used to estimate responses to therapy with the selected dose. . The main therapeutic objectives of GH therapy in children with GHD are to normalize height during childhood and to reach normal adult height . Treatment of GHD must be started in pre-pubertal age as early as possible. Early and correct diagnosis is fundamental for successful GH therapy . Monitoring of growth hormone replacement effectiveness is accomplished by monitoring the serum IGF-1 concentration, which should be maintained at the mid-normal range. . ∆ HSDS >1 SDS to be a good response and ∆HSDS < 0.4 SDS to be a poor growth response in GHD (these values are age dependent and require further validation). . Serial IGF-1 measurements during GH therapy are useful to assess efficacy, safety, and compliance and have been proposed as a tool for adjusting the GH dose. No other biochemical tests are routinely recommended in GH-treated patients. . Patients with GH deficiency demonstrated increased total body fat, atherothrombotic and proinflammatory abnormalities, dyslipidemia and insulin resistance. They also showed increased vessel intima-media thickness, high peripheral vascular resistance and enhanced aorta stiffness. . Patients with childhood-onset GHD have decreased left ventricular mass and hypokinetic syndrome, a state characterized by low ejection fraction, low cardiac output, and high peripheral vascular resistance. . Side effects of growth hormone administration should be monitored. These may include edema, paresthesia, carpal tunnel syndrome, arrhythmia, and glucose intolerance. They are more common in older obese patients with high IGF-1 levels.

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GH Therapy Alternatives Anabolic Steroids Oxandrolone has been shown to increase height velocity in the short term in several controlled studies but does not significantly increase predicted or measured adult height. Low-dose testosterone therapy causes short-term acceleration of linear growth with minimal or no advancement of bone age or decrease in adult height potential. Although both of these drugs are useful in males with CDGP with mild to moderate short stature (> −2.5 SDS), testosterone is the most appropriate treatment for boys with CDGP with an adult height prediction within the normal range. Oxandrolone offers the advantage of oral administration, but the disadvantages of being weakly androgenic and carrying the remote risk of hepatotoxicity. IGF-1 IGF-1 is approved for short stature with severe IGF-1 deficiency associated with normal GH secretion (GH insensitivity). In idiopathic short stature children who do not respond to GH treatment, IGF-1 therapy is a theoretical option; however, data are lacking regarding efficacy and safety in this population. GnRH Analogs (GnRHa) Monotherapy with GnRHa in both sexes has shown a small and variable effect on adult height gain and is generally not recommended. Concerns have been raised regarding potential adverse effects of GnRHa, including on short-term bone mineral density and on the psychological consequences of delaying puberty. Combination therapy with GnRHa and GH, however, has potential value if the GnRHa is used for at least 3 years. Aromatase Inhibitors The use of third-generation aromatase inhibitors plays an emerging role in the treatment of specific endocrine disorders in children. They are well tolerated and are available as a convenient once-daily oral dose; however, safety information regarding long-term effects on bone mineral acquisition, spermatogenesis, and exposure to supraphysiological testosterone levels are still needed. In addition, definitive data for most indications are still lacking. AIs when combined with antiandrogen are Blueprint in Pediatric Endocrinology 241

the treatment of choice for male limited peripheral precocious puberty, additional evidence in support of the specific combination of bicalutamide with anastrozole. Use of similar combined therapy as an adjunct to traditional therapy for congenital adrenal hyperplasia, allowing lower glucocorticoid dosages, may prove effective to increase adult height and prevent early virilization; results of a long-term study testing this hypothesis should be forthcoming. Efficacy of AIs in girls with McCune-Albright syndrome seems to be limited; progression of ovarian cyst formation may further curtail utility in this group of patients. Use of AIs in boys with idiopathic short stature and short stature associated with growth hormone deficiency or constitutional delay may increase adult height modestly; however, up to now data on adult height are lacking, and there is no information identifying which children are likely to benefit most. Additional controlled studies are required before this therapy can be routinely recommended to augment adult height. There is no current evidence that third-generation AIs reduce pubertal gynaecomastia; studies testing the hypothesis that benefit would derive from initiating therapy before 6 months and establishing a more effective blockade need to be performed. Thus, despite the potential promise of these agents in the treatment of selected pediatric endocrine disorders, there is an urge to physicians to exercise caution in the use of these agents outside of controlled clinical trials. Psychological Counseling Psychosocial interventions to support the adaptation process to short stature and to enhance personal resources for coping with stress experiences as well as social action to reduce prejudices are worthwhile to consider instead of or as an adjunct to hormone treatment. No data have been reported about the effect of such interventions. Growth Hormone Insensitivity Short stature due to biologically inactive GH is characterized by normal to high levels of circulating GH by immunoassay but by lower levels of GH when assessed by cell proliferation, receptor binding, or receptor activation assays. The mutant molecule has subnormal activities in immunofunction, receptor binding and activation of the Jak2/Stat5 signaling pathway. 242 Chapter 6: Growth and Growth Disorders

In the 1960s, Zvi Laron described a novel clinical phenotype of unknown etiology that strongly resembled familial, congenital growth hormone (GH) deficiency, but was associated with elevated serum GH concentrations. This clinical phenotype, known as Laron syndrome, initially was attributed to the secretion of biologically inactive GH in these subjects, although they also were found to have inadequate responses to human pituitary-derived GH. IGF-1 is a GH-dependent growth factor; IGF-1 deficiency became a plausible mechanism for Laron syndrome. In a series of subsequent investigations, the low serum IGF-1 concentrations characteristic of Laron syndrome were linked to GH insensitivity resulting from mutations or deletions in the GH receptor gene. These observations formed the foundation for the concept of primary IGF-1 deficiency (primary IGFD), although later studies uncovered multiple other etiologies for this pathophysiological state. IGFD can be divided into primary and secondary causes. Secondary IGFD includes those disorders in which IGF deficiency results from defects of GH production, on either a hypothalamic or pituitary basis. Secondary IGFD can be the consequence of damage to the hypothalamus and / or pituitary resulting from trauma, infection, tumors, radiation, inflammation, and so on, as well as an increasingly recognized group of molecular defects in pituitary development. Primary IGFD represents a constellation of disorders characterized by decreased IGF-1 production in the presence of normal or even elevated GH secretion (states of insensitivity to GH action). To date, eight different molecular defects have been identified as causes of primary IGFD. Growth hormone insensitivity is caused by disruption of pathways distal to production of GH. Laron syndrome involves mutations of the GH receptor. Children with this condition clinically resemble those with severe IGHD. Birth length tends to be about 1 SD below the mean, and severe short stature with lengths more than 4 SD below the mean is present by 1 year of age. Resting and stimulated GH levels tend to be high, and IGF-1 levels are low. The GH receptor has an extracellular GH-binding domain, a transmembrane domain, and an intracellular signaling domain. Mutations in the extracellular domain interfere with binding of GH. Serum growth hormone binding protein (GHBP) activity, representing the circulating form of the membrane receptor for GH, is generally low. Mutations in the transmembrane domain can interfere with Blueprint in Pediatric Endocrinology 243

anchoring of the receptor to the plasma membrane. In these cases, circulating GHBP activity is normal or high. Mutations in the intracellular domain interfere with JAK/STAT signaling. Post-Receptor Forms of GH Insensitivity Some children with severe growth failure, high GH and low IGF-1 levels, and normal GHBP levels, have abnormalities distal to the GH binding and activation of the GH receptor. Several have been found to have mutations in the gene-encoding signal transducer and activator of transcription 5b (STAT5b). Disruption of this key intermediate connecting receptor activation to gene transcription produces growth failure similar to that seen in Laron syndrome. These patients also suffer from chronic pulmonary infections, consistent with important roles for STAT5b in interleukin and cytokine signaling. IGF-1 gene Abnormalities Abnormalities of the IGF-1 gene produce severe prenatal as well as postnatal growth impairment. Microcephaly, mental retardation, and deafness are present in patients with exon deletion and a missense mutation. These patients can be expected to respond to recombinant IGF- 1 treatment. IGF-binding Protein Abnormalities Mutation of the gene encoding the acid-labile subunit of the circulating IGF-1, IGF-BP3 acid-labile subunit complex is associated with short stature. Total IGF-1 levels are very low. The index case, with homozygosity for an ALS mutation, did not show an increase in IGF-1 levels or an increase in growth rate during GH treatment. IGF-1 Receptor Gene Abnormalities Mutations of the IGF-1 receptor also compromise prenatal and postnatal growth. The phenotype does not appear to be as severe as that seen with absence of IGF-1. Adult heights are closer to the normal range, and affected individuals do not have mental retardation or deafness. Diagnosis of Primary IGFD IGF-1 deficiency may occur as a result of various GH-deficient states, reflecting defects at the hypothalamic or pituitary level; when this is found, the IGF-1 deficiency is considered secondary. In some 244 Chapter 6: Growth and Growth Disorders

situations, however, such as Laron syndrome, IGF-1 deficiency is present despite adequate or even elevated GH levels. A hormone deficiency that is present despite adequate stimulation for its production and secretion is said to be primary (e.g. primary hypothyroidism, primary hypocortisolism). The primary IGFD state is defined by the presence of short stature, normal or elevated GH levels, and IGF-1 deficiency. Treatment Prolonged therapy with rhIGF-1 to children with GHIS and to those with GH gene deletion has proved to be safe and effective with side effects presenting mainly when high doses of rhIGF-I have been used. However, treatment with rhIGF-1 given systemically may not completely replace the local response of target tissues to locally produced IGF-1. Clinical trial of treatment with the rhIGF-I/IGFBP-3 complex in GHIS patients is currently in progress. Key Points . The integrity of the GH-IGF-1 axis is essential for normal linear growth in childhood. . Defects in either GH secretion or action will result in reducing serum IGF-1, the key growth promoting peptide. . The identification of several new genetic causes of GH deficiency or insensitivity has broadened the range of etiologies responsible for GH disorders. . While classical endocrine tests remain the most reliable for assessing the GH-IGF-1 axis, analysis of the appropriate candidate genes can contribute to the precise definition of the pathogenesis of the growth disorder. Overgrowth in the Fetuses Maternal diabetes constitutes the most common cause of infants who are large for gestational age (LGA). Even in the absence of clinical symptoms or a family history, the birth of an excessively large infant should lead to evaluation for maternal (or gestational) diabetes. A group of disorders associated with excessive somatic growth and growth of specific organs has been described and is collectively referred to as overgrowth syndromes. These disorders appear to be caused by excess Blueprint in Pediatric Endocrinology 245

availability of insulin-like growth factor 2. The best described of these syndromes is the Beckwith-Weidman syndrome, which is an overgrowth malformation syndrome that occurs with an incidence of 1:13,700 births. It manifests as a fetal overgrowth syndrome in which hypertrophy dominates the clinical picture. Typically, macroglossia, hepatosplenomegaly, nephromegaly, and hypoglycemia secondary to hyperinsulinemia due to pancreatic β-cell hyperplasia in an LGA baby make up the clinical picture at birth. These children are predisposed to a specific subset of childhood neoplasm, including Wilms tumor and adrenocortical carcinoma. Over expression of IGF-2 in BWS may be caused by a number of genetic disruptions including gene duplication, loss of heterozygosity or loss of imprinting of the IGF-2 gene. Various lines of investigation have localized ―imprinted‖ genes involved in BWS and associated childhood tumors to chromosome 11p. Soto's Syndrome (cerebral gigantism) Affected children with Soto's syndrome are above the 90th percentile for both length and weight at birth; macrocrania may also be noted at that time. Soto's syndrome is caused by haploinsufficiency of the NSD1 gene (nuclear receptor SET domain–containing gene–1). Although it is characterized by rapid growth, there is no evidence that Soto's syndrome is an endocrine disorder. A hypothalamic defect has been suggested as a cause, but none has been demonstrated functionally or at necropsy. Growth is rapid, and by 1 year of age, affected infants are greater than the 97th centile in height. Accelerated growth continues for the first 4–5 year and then returns to a normal rate. Puberty usually occurs at the normal time but may occur slightly early. Adult height is usually in the upper normal range. The hands and feet are large, with thickened subcutaneous tissue. The head is large and dolichocephalic, the jaw is prominent, there is hypertelorism, and the eyes have an antimongoloid slant. Clumsiness and awkward gait are characteristic, and affected children have great difficulty in sports, in learning to ride a bicycle, and in other tasks requiring coordination. Some degree of mental retardation affects most patients; in some children, perceptual deficiencies may predominate. Osseous maturation is compatible with the patient's height. GH and IGF-1 levels and results of other endocrine studies are usually normal; there are no distinctive laboratories or radiologic markers for the syndrome. Abnormal electroencephalograms are common; other studies 246 Chapter 6: Growth and Growth Disorders

frequently reveal a dilated ventricular system. Affected patients may be at increased risk for neoplasia; hepatic carcinoma and Wilms, ovarian, and parotid tumors have been reported.

Fig. (6-10): Showed Macrocrania in Soto's Syndrome. Tall Stature The normal distribution of height predicts that 3 % of the population will be taller than 2 SD (97th centile) above the meanfor age, sex and race. However, the social acceptability and even desirability of tallness, makes tall stature an uncommon complaint. Even in females, tall stature has become more socially acceptable.

Fig. (6-11): Showing Clinical Features of XYY Syndrome. Blueprint in Pediatric Endocrinology 247

Differential Diagnosis Normal variant, familial or constitutional tall stature is by far the most common cause. Almost invariably, a family history of tallness can be elicited, and no organic pathology is present. The child is often tall throughout childhood and enjoys excellent health. The parent of the constitutionally tall adolescent may reflect unhappily upon his or her own adolescence as a tall teenager. There are no abnormalities in the physical examination, and the laboratory studies, if obtained, are always negative. . Fetal overgrowth could be caused by, maternal diabetes, cerebral gigantism this is called as Soto's syndrome, Beckwith-Weidman syndrome and obese mothers. . Klinefelter syndrome (XXY syndrome) is a common (1: 500- 1000 live male births). Abnormalities associated with tall stature are; mild mental retardation, gynaecomastia, and decreased upper to lower body segment ratio. The testes are invariably small although androgen production by Leydig cells is often in the low-normal range. Spermatogenesis and Sertoli cell function are defective, and infertility results. . XYY syndrome is associated with tall stature and possible behavioral and mental problems with no dysmorphic features. . Marfan's syndrome is an autosomal dominant connective tissue disorder consisting of tall stature, increased arm span, and decreased upper to lower body segment ratio. Additional abnormalities include arachnodactyly, ocular abnormalities, and cardiac anomalies. . Homocystinuria is an autosomal recessive inborn error of amino acid metabolism causing mental retardation when untreated, and many of its features resemble Marfan syndrome, particularly ocular manifestations. . Hyperthyroidism in adolescents is associated with rapid growth but normal adult height. It is almost always caused by Graves's disease and is much more common in females. . Exogenous obesity is a common condition in adolescence and may be associated with rapid linear growth and early maturation; adult height is typically normal. 248 Chapter 6: Growth and Growth Disorders

Fig. (6-12): Showing Clinical Features of Marfan's Syndrome. Diagnosis of tall stature The purpose of the diagnostic evaluation of tall stature is to distinguish the commonly occurring normal variant constitutional variety from the rare pathologic conditions. Often, when the history is suggestive of familial tall stature and the physical examination is entirely normal, no laboratory tests are indicated. It is valuable to obtain a bone age radiograph to be able to predict adult height, which serves as a basis for discussions with the family and for management decisions. If, however, the history is suggestive for any of the above-mentioned disorders or the physical examination reveals abnormalities, additional laboratory tests should be obtained. Insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3) are excellent screening tests for GH excess and can be verified with a glucose suppression test. Laboratory evidence of GH excess mandates MRI evaluation of the pituitary. Chromosome analysis is useful in males, especially when the upper to lower body segment ratio is decreased or when mental retardation is present. If Marfan syndrome or Homocystinuria is suspected from the physical examination, referral to a cardiologist and an ophthalmologist should be made. Thyroid function Blueprint in Pediatric Endocrinology 249

tests are useful to diagnose or rule out hyperthyroidism when this disorder is suspected. Precocious puberty, whether mediated centrally (increased gonadotropin secretion) or peripherally (increased secretion of androgens, estrogens, or both), results initially in accelerated linear growth in childhood, mimicking the pubertal growth spurt. Because skeletal maturation is also accelerated, adult height is frequently compromised. Although delayed puberty may be associated with short stature in childhood, as with constitutional delay, failure to eventually enter puberty and complete sexual maturation may result in sustained growth during adult life, with ultimate tall stature. The report of tall stature with open epiphyses resulting from a mutation of the estrogen receptor in a man with normal male sexual maturation underscores the fundamental role of estrogen in promoting epiphyseal fusion and termination of normal skeletal growth. Aromatase deficiency leads to tall stature through similar pathways. Furthermore, androgen insensitivity is associated with tall stature in girls, demonstrating a role for androgen in this process. Management Reassurance of the family and the patients is the key to the management of normal-variant tall stature. The use of the bone age to predict adult height may provide some comfort, as will general supportive discussions on the social acceptability of this condition. Treatment is available for girls and boys with excessive growth, its use should be restricted to patients with a predicted adult height of > 3 SD above the mean (188cm in males, 178 cm in females) and evidence of significant psychosocial impairment. For the family that feels strongly about treatment, a trial of sex steroids may be considered. Such therapy is designed to accelerate puberty and epiphyseal fusion and is therefore of little benefit when given in late puberty; therapy is initiated ideally prepubertal or in early puberty. In boys, treatment should begin before the bone age reaches 14 year; testosterone enanthate is used at a high dose of 500 mg intramuscular every 2 weeks for 6 months. In females, oral estrogen in various doses has successfully reduced the predicted height by 5–10 cm on average. Therapy must begin, before the bone age has reached 12 years. Oral ethinyl estradiol at a dose of 0.15–0.5 mg/day 250 Chapter 6: Growth and Growth Disorders

or alternative conjugated estradiol until cessation of growth occurs has been used successfully in girls. If necessary, a progestational agent can be added after 1 year of unopposed estrogen. Short-term side effects of estrogen treatment for tall stature include menstrual irregularities, weight gain, nausea, limb pain, galactorrhea, benign breast disease, cholelithiasis, hypertension, and thrombosis. Reduced fertility later in life may be a potential long-term complication. The lack of extensive experience with this form of therapy and the risks involved should be carefully weighed and discussed with the family before embarking on therapy. The mechanism of estrogen action involves effects on both GH and IGF production as well as its action on the epiphysis. Estrogen mediates epiphyseal fusion in both females and males. In prepubertal girls, adult height is reportedly decreased by as much as 5–6 cm relative to pretreatment predictions. When therapy is initiated after the onset of puberty, the decrement in adult height will not be so large. Therapy in boys with tall stature is even more problematic. Estrogen is likely to be most efficacious in accelerating epiphyseal fusion but is obviously undesirable in boys. Androgens also accelerate skeletal maturation, presumably via aromatization, to estrogen but are associated with virilization. References and Further Reading

1. Biller BM. Concepts in the diagnosis of adult growth hormone deficiency. Horm Res. 2007; 68(5):5965. 2. Eugster EA, Pescovitz OH. New revelations about the role of STATs in stature. N Engl J Med. 2003 Sep 18; 349(12):1110-1112. 3. Cohen P. Overview of the IGF-I system. Horm Res. 2006; 65(1):3-8. 4. Allen DB, Fost N. hGH for short stature: ethical issues raised by expanded access. J Pediatr. 2004 May; 144(5): 648-652. 5. Cohen P. Consensus statement on ISS. ISS Consensus Conference. Santa Monica, CA; 2007. 6. Allen DB. Growth hormone therapy for short stature: is the benefit worth the burden? Pediatrics. 2006 Jul; 118(1): 343-348. 7. Hochberg Z. Mechansims of steroid impairment of growth. Hormone Res. 2002; 58(1):33-38. Blueprint in Pediatric Endocrinology 251

8. Huiming Y, Chaomin W. Recombinant growth hormone therapy for X-linked hypophosphatemia in children. Cochrane Database Syst Rev. 2005(1):CD004447. 9. Van den Berghe G. Neuroendocrine pathobiology of chronic critical illness. Crit Care Clin. 2002 Jul; 18(3):509- 528. 10. Mahesh S, Kaskel F. Growth hormone axis in chronic kidney disease. Pediatr Nephrol. 2008 Jan; 23(1):41-48. 11. Simon D. Puberty in chronically diseased patients. Horm Res. 2002; 57(2):53- 56. 12. Nissel R, Lindberg A,Mehls O,Haffner D. Factors predicting the near-final height in growth hormone-treated children and adolescents with chronic kidney disease. J Clin Endocrinol Metab. 2008 Apr; 93(4):1359-1365. 13. Bechtold S, Ripperger P, Dalla Pozza R, et al. Growth hormone increases final height in patients with juvenile idiopathic arthritis: data from a randomized controlled study. J Clin Endocrinol Metab. 2007 Aug; 92(8):3013-3018. 14. Simon D, Prieur AM, Quartier P, Charles Ruiz J, Czernichow P. Early recombinant human growth hormone treatment in glucocorticoid-treated children with juvenile idiopathic arthritis: a 3-year randomized study. J Clin Endocrinol Metab. 2007 Jul; 92(7):2567-2573.

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Chapter 7

The Pituitary Gland

. Introduction . Pituitary gland . Growth Hormone . Prolactin . Thyroid-Stimulating Hormone . Adrenocorticotropic Hormone . Luteinizing Hormone and Follicle-Stimulating Hormone . Posterior pituitary cell types . Antidiuretic Hormone . Oxytocin . Hypopituitarism . Genetic forms of pituitary hormone deficiency o HESX1 o LHX3 o LHX4 o PTX2 o PROP1 o POU1F1 (PIT1) . Hypopituitarism in neonates . Hypopituitarism in older infants and children . Growth hormone deficiency o Isolated growth hormone deficiency o Combined growth hormone deficiency . Acquired hypopituitarism . Diagnosis of hypopituitarism o Corticotrophin deficiency o Insulin-induced Hypoglycemia Test o Synacthen (Cosyntropin) stimulation test o Thyrotropin deficiency o Gonadotropin deficiency o Growth hormone deficiency o Adrenocorticotropic hormone deficiency o Thyroid-stimulating hormone deficiency

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o Luteinizing hormone & follicle-stimulating hormone deficiency o Antidiuretic hormone & physiology of water balance . Approach to patient with hypernatremia . Central diabetes insipidus . Nephrogenic diabetes insipidus . Treatment of central diabetes insipidus . Treatment of nephrogenic diabetes insipidus . Suggested doses of Desmopressin . Water deprivation test interpretation . The syndrome of inappropriate Antidiuretic hormone o Causes of syndrome of inappropriate ADH secretion o Treatment of syndrome of inappropriate ADH secretion . Acute hyponatraemia . Chronic hyponatraemia . Persistent chronic SIADH . Cerebral salt wasting syndrome . Hyperpituitarism o Excess growth hormone secretion and pituitary gigantism o Diagnosis of growth hormone excess . Treatment of growth hormone oversecretion . Prolactinoma . Corticotropinoma

Introduction The hypothalamic-pituitary axis (HPA) is responsible for the coordination of numerous essential endocrine functions. The HPA has far-reaching endocrine influence; it affects the secretions of the thyroid, adrenals, and gonads. The HPA also influences growth, milk production and water concentration in the body. In addition, the HPA affects several nonendocrine functions, including appetite control, thermal regulation, and activity of the autonomic nervous system. Hormonal signals or neurosignals from the hypothalamus control almost all secretions of the pituitary gland. The pituitary gland is located in the anterior fossa in the sella turcica, which is situated posteriorly to the eyes. The optic nerves and chiasm may be compressed by the growth of a pituitary tumor, typically a bitemporal hemianopia, which can result in loss or impairment of vision. The pituitary is composed of the adenohypophysis, or anterior lobe, and the Neurohypophysis, or posterior lobe. The pituitary gland is connected to the hypothalamus by the pituitary stalk The major biologically active hormones released into systemic circulation include , growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL). The anterior pituitary is primarily regulated by neuropeptide- releasing and release-inhibiting hormones produced in the hypothalamus. These regulatory hormones are transported to the anterior pituitary via the pituitary portal system circulation. The release-stimulating hormones produced by the hypothalamus include growth hormone–releasing hormone (GHRH), corticotrophin-releasing hormone (CRH), thyrotropin- releasing hormone (TRH), and gonadotropin-releasing hormone (GnRH). Prolactin secretion is distinct from the other anterior pituitary hormones with its secretion inhibited by hypothalamic dopamine. In addition, Antidiuretic hormone (ADH) produced in the hypothalamus acts synergistically with CRH to promote ACTH release. GH is secreted in a pulsatile fashion and is under the regulation of the hypothalamic hormones GHRH and somatostatin. In plasma the majority of GH circulates in the free form but about 40% of GH circulates bound to GH binding protein (GHBP) .Most of the circulating IGF-1 is derived primarily from hepatic production and it is believed that one of the main

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functions of circulating IGF-1 is to mediate GH negative feedback. A negative feedback loop occurs such that the hormones produced in the target glands feedback to inhibit the release of their respective regulatory pituitary and hypothalamic factors. For example, hypothalamic TRH stimulates TSH release, which, in turn, stimulates the thyroid gland resulting in increased serum levels of thyroxin (T4) and triiodothyronine (T3). When they have reached sufficient levels, T3 and T4 suppress TRH and TSH release. The posterior pituitary consists of neural tissue that descends from the floor of the third ventricle. In contrast to the anterior pituitary hormones, the posterior pituitary hormones (ADH, oxytocin) are synthesized by cell bodies in the hypothalamus and transported along the neurohypophyseal tract of the pituitary stalk. Release of these hormones occurs in response to neurohypophyseal stimuli.

Fig. (7-1): Showing The Position of Pituitary Gland and Related Structures. Growth Hormone (GH) Human GH is a 191-amino-acid single-chain polypeptide that is synthesized, stored, and secreted by somatotrophs in the pituitary. GH is secreted in a pulsatile fashion under the regulation of hypothalamic hormones. The alternating secretion of growth hormone–releasing hormone (GHRH), which stimulates GH release, and somatostatin, which inhibits GH release, accounts for the rhythmic secretion of GH. Peaks of GH occur when peaks of GHRH coincide with troughs of somatostatin. Blueprint in Pediatric Endocrinology 257

Ghrelin, a peptide produced in the arcuate nucleus of the hypothalamus and in much greater quantities by the stomach, also stimulates GH secretion. Physiological factors also have a role in the stimulation and inhibition of GH. Sleep, exercise, physical stress, trauma, acute illness, puberty, fasting, and hypoglycemia stimulate the release of GH, whereas hyperglycemia, hypothyroidism, and glucocorticoids inhibit GH release.

Fig. (7-2): Showing Pulsatile Pattern of GH Secretion With Nocturnal Maximum Release. The biologic effects of GH include increases in linear growth, bone thickness, soft tissue growth, and protein synthesis, fatty acid release from adipose tissue, insulin resistance, and blood glucose levels. The mitogenic actions of GH are mediated through increases in the synthesis of insulin-like growth factor-1 (IGF-1), formerly named somatomedin C, which is a 70-amino-acid single-chain peptide coded for by a gene on the long arm of chromosome 12. IGF-1 has considerable homology to insulin. Circulating IGF-1 is synthesized primarily in the liver and formed locally in mesodermal and ectodermal cells, particularly in the growth plate of children, where its effect is exerted by paracrine or autocrine mechanisms. Circulating levels of IGF-1 are related to blood levels of GH and to nutritional status. IGF-1 circulates bound to several different binding proteins. The major one is IGF-BP3, which is decreased in GH-deficient children. Human recombinant IGF-1 may have therapeutic potential in conditions characterized by end organ resistance to GH such as Laron syndrome and the development of antibodies to administered GH. IGF-2 is a 67-amino-acid single-chain protein that is coded for by a gene on the short arm of chromosome 11. It has homology to IGF-1. Less is known about its physiologic role, but it appears to be an important mitogen in bone cells, where it occurs in a concentration many times higher than that of IGF-1. 258 Chapter 7: The Pituitary Gland

Fig. (7-3): Showing GH effects on various tissues.

Prolactin (PRL) PRL, is a 199-amino-acid peptide made in pituitary lactotrope. The regulation of PRL is unique because PRL is consistently secreted unless it is actively inhibited by dopamine, which is produced by neurons in the hypothalamus. Disruption of the hypothalamus or pituitary stalk can result in elevated PRL levels. Dopamine antagonists, states of primary hypothyroidism, administration of thyrotropin-releasing hormone (TRH), physiologic stress (shock) and pituitary tumors result in increased serum levels of PRL. Dopamine agonists and processes causing destruction of the pituitary cause reduced levels of PRL. The primary physiologic role of PRL is the initiation and maintenance of lactation. PRL prepares the breasts for lactation and stimulates milk production postpartum. During pregnancy, PRL stimulates the development of the milk secretory apparatus, but lactation does not occur because of the high levels of estrogen and progesterone. After delivery, the estrogen and progesterone levels drop and physiologic stimuli such as suckling and nipple stimulation signal PRL release and initiate lactation. Blueprint in Pediatric Endocrinology 259

Thyroid-Stimulating Hormone (TSH) TSH consists of 2 glycoprotein chains (α and β) linked by hydrogen bonding; the α-subunit is composed of 89 amino acids and is identical to other glycoprotein (FSH, LH, human chorionic gonadotropin (hCG), and the β-subunit of 112 amino acids is specific for TSH). TSH is stored in secretory granules and released into circulation primarily in response to thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus. TRH is released from the hypothalamus into the hypothalamic-pituitary portal system, ultimately stimulating TSH release from pituitary thyrotrophs. TSH stimulates release of thyroxin (T4) and triiodothyronine (T3) from the thyroid gland through the formation of cyclic adenosine monophosphate (cAMP) and the G-protein second messenger system. In addition to the negative feedback inhibition by T3, the release of TRH and TSH are also inhibited by dopamine, somatostatin, and glucocorticoids. Deficiency of TSH results in inactivity and atrophy of the thyroid gland, whereas excess TSH results in hypertrophy and hyperplasia of the thyroid gland. Adrenocorticotropic Hormone (ACTH) Is a 39-amino-acid single-chain peptide that is derived by proteolytic cleavage from POMC secretion of ACTH is regulated by corticotrophin- releasing hormone (CRH), a 41-amino-acid peptide found predominantly in the median eminence but also in other areas in and outside the brain. ACTH is secreted in a diurnal pattern. It acts on the adrenal cortex to stimulate cortisol synthesis and secretion. ACTH and cortisol levels are highest in the morning at the time of waking, are low in the late afternoon and evening, and reach their nadir 1 to 2 hour after the beginning of sleep. ACTH also appears to be the principal pigmentary hormone in humans. Similar to TRH and TSH, CRH and ACTH function through the formation of cAMP and the G-protein second messenger system. Although CRH is the primary regulator of ACTH secretion, other hormones have a role. Arginine vasopressin (AVP), oxytocin, angiotensin II, and cholecystokinin stimulate release of CRH and ACTH, whereas atrial natriuretic peptide (ANP) and opioids inhibit release of CRH and ACTH. Cortisol inhibits CRH and ACTH. Physiologic conditions such as stress, fasting, and hypoglycemia also stimulate release of CRH and ACTH. 260 Chapter 7: The Pituitary Gland

Luteinizing Hormone (LH) & Follicle-Stimulating Hormone (FSH) They contain the same α-subunit as TSH and hCG but distinct β- subunits. Receptors for FSH on the ovarian granulosa cells and on testicular Sertoli cells mediate FSH stimulation of follicular development in the ovary and of gametogenesis in the testis. On binding to specific receptors on ovarian theca cells and testicular Leydig cells, LH promotes luteinization of the ovary and Leydig cell function of the testis. The receptors for LH and FSH belong to a class of receptors with 7 membrane-spanning protein domains. Receptor occupancy activates adenylyl cyclase through the mediation of G-proteins. Luteinizing hormone–releasing hormone, a decapeptide, has been isolated, synthesized, and used therapeutically. Secretion of LH is inhibited by androgens and estrogens, and secretion of FSH is suppressed by gonadal production of inhibin, which is a glycoprotein produced by the Sertoli cells. Inhibin consists of α- and β-subunits joined by disulfide bonds. The β-β dimer (activin) also occurs; its biologic effect is to stimulate FSH secretion. The biologic features of inhibin and activin are being delineated. In addition to its endocrine effect, activin has paracrine effects in the testis. It facilitates LH-induced testosterone production, indicating a direct effect of Sertoli cells on Leydig cells. Posterior Pituitary Cell Types The posterior lobe of the pituitary is part of a functional unit, the neurohypophysis, which consists of the neurons of the supraoptic and paraventricular nuclei of the hypothalamus; neuronal axons, which form the pituitary stalks; and neuronal terminals in the median eminence or in the posterior lobe. Antidiuretic Hormone (ADH) ADH regulates water conservation at the level of the kidney by increasing the permeability of the renal collecting duct to water. ADH stimulates translocation of water channels through its interaction with vasopressin 2 (V2) receptors in the collecting duct, which act through G- proteins to increase adenylyl cyclase activity and increase permeability to water. V2 receptors also mediate the von Willebrand factor and tissue plasminogen activator. At higher concentrations, ADH activates V1 receptors in smooth muscle cells and hepatocytes and exerts pressor and Blueprint in Pediatric Endocrinology 261

glycogenolytic effects through mobilization of intracellular calcium stores. Separate V3 receptors medicate stimulation of ACTH secretion. These effects involve phosphatidylinositol hydrolysis rather than cyclic AMP production. ADH and its accompanying protein, neurophysin II, are encoded by the same gene. A single preprohormone is cleaved, and the two are transported to neurosecretory vesicles in the posterior pituitary. The two are released in equimolar amounts. ADH has a short half-life and responds quickly to changes in hydration. The stimuli for its release are increased plasma osmolality, perceived by osmoreceptors in the hypothalamus, and decreased blood volume, perceived by baroreceptors in the carotid sinus of the aortic arch. Oxytocin Oxytocin stimulates uterine contractions at the time of labor and delivery in response to distention of the reproductive tract, and it stimulates smooth muscle contraction in the breast during suckling, which results in milk let-down. Hypopituitarism Hypopituitarism refers to the partial or complete deficiency of two or more pituitary hormones. It may arise as a congenital defect in the development of the pituitary gland or as a result of acquired diseases of the pituitary gland, the parasellar structures, or the hypothalamus. Multiple pituitary hormone deficiency (MPHD) is rare in childhood, with a possible incidence of fewer than 3 cases per million people per year. The most common pituitary hormone deficiency, growth hormone deficiency (GHD), is much more frequent; a prevalence of 1 case in 3500 children. With knowledge of the genes that direct pituitary development or hormone production, an increasing proportion of cases can be attributed to specific genetic disorders. Mutations in these genes account for 13% of isolated growth hormone deficiency (IGHD) and 20% of multiple pituitary hormone deficiency (MPHD) cases. The likelihood of finding mutations is increased by positive family histories and decreased in cases with ACTH deficiency.

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Causes They can be divided into categories of congenital and acquired causes. Congenital Causes . Perinatal insults (e.g., traumatic delivery, birth asphyxia,.etc). . Genetic disorders. . Isolated growth hormone deficiency types IA, IB, II, and III. . MPHD (e.g. PIT1, PROP1 gene mutations). . Septo-optic dysplasia. . Isolated gonadotropin deficiency (e.g., KAL, KISS1R). . Developmental CNS defects. . Anencephaly. . Holoprosencephaly. . Pituitary aplasia or hypoplasia. . Interrupted pituitary stalk. . Absent or ectopic neurohypophysis. . Pallister-Hall syndrome. Genetic Forms of Pituitary Hormone Deficiency Sequentially expressed transcriptional activation factors direct the differentiation and proliferation of anterior pituitary cell types. These proteins are members of a large family of DNA-binding proteins resembling homeobox genes. Mutations produce different forms of multiple pituitary hormone deficiency. The HESX1, LHX3, LHX4, and PTX2 genes are expressed at early stages of pituitary development. They are also expressed in other organs. Mutations in these genes tend to produce phenotypes that extend beyond hypopituitarism to include abnormalities in other organs. HESX1 The HESX1 gene is expressed in precursors of all 5 cell types of the anterior pituitary early in embryologic development. Mutations result in a Blueprint in Pediatric Endocrinology 263

complex phenotype with defects in development of the optic nerve. Heterozygote for loss-of-function mutations shows the combinations of isolated GH deficiency and optic nerve hypoplasia. Homozygote may have full expression of septo-optic dysplasia (SOD), which manifests incomplete development of the septum pellucidum with optic nerve hypoplasia and other midline abnormalities. Clinical observation of nystagmus and visual impairment in infancy leads to the discovery of optic nerve and brain abnormalities. SOD is associated with anterior and/or posterior pituitary hormone deficiencies in 25% of patients. Patients often have the triad of a small anterior pituitary gland, an attenuated pituitary stalk, and an ectopic posterior pituitary bright spot. The great majority of SOD cases do not have HESX1 mutations. LHX3 LHX3 activates the α-GSU promoter and acts synergistically with POU1F1 to increase transcription from the PRL, β-TSH, and POU1F1 promoters. The hormonal phenotype produced by recessive loss-of- function mutations in this gene resembles that produced by PROP1 mutations. There are deficiencies of GH, PRL, TSH, LH, and FSH but not ACTH. It is unclear whether the deficiencies are present from birth or whether they appear later in childhood. Some affected individuals show enlargement of the anterior pituitary. LHX4 Dominantly inherited mutations in the LHX4 gene consistently produce GH deficiency, with the variable presence of TSH and ACTH deficiencies. Additional findings may include a small, V-shaped pituitary fossa, Chiari -1 malformation, and ectopic posterior pituitary. PTX2 Rieger syndrome is a complex phenotype caused by mutations in the PTX2 transcription factor gene. This gene is also referred to as RIEG1. It is expressed in multiple tissues, including the anterior pituitary gland. In addition to variable degrees of anterior pituitary hormone deficiency, children with Rieger syndrome have coloboma of the iris and abnormal development of the kidneys, gastrointestinal tract, and umbilicus.

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PROP1 PROP1 is found in the nuclei of somatotrophs, lactotropes, and thyrotrophs. Its roles include turning on POU1F1 expression, hence its name ―prophet of PIT1‖ Mutations of PROP1 are the most common explanation for recessive MPHD. These mutations are 10 times as common as the combined total of mutations in other pituitary transcription factor genes. One- and two-base-pair deletions in exon 2 are most common, followed by missense, nonsense, and splice site mutations. Anterior pituitary hormone deficiencies are seldom evident in the neonatal period. Growth in the first year of life is considerably better than with POU1F1 defects. The median age at diagnosis of GH deficiency is around 6 year. Recognition of TSH deficiency is delayed relative to recognition of GH deficiency. Basal and TRH-stimulated PRL levels tend to be higher than in POU1F1 mutations. Most children with PROP1 mutations develop LH and FSH deficiency. Some enter puberty spontaneously and then retreat from puberty. Girls experience secondary amenorrhea, and boys show regression of testicular size and secondary sexual characteristics. Partial deficiency of ACTH develops over time in about 30% of patients with PROP1 defects. Anterior pituitary size is small in most patients, but in some there is progressive enlargement of the pituitary. A central mass originates within the sella turcica but may extend above it. The cellular content of the mass during the active phase of enlargement is not known. With time, the contents of the mass appear to degenerate, with multiple cystic areas. The mass may persist as a nonenhancing structure or may disappear completely, leaving an empty sella turcica. At different stages, MRI findings can suggest a microadenoma, macroadenoma, craniopharyngioma, or Rathke's pouch cyst. POU1F1 (PIT1) POU1F1 (formerly PIT1) was identified as a nuclear protein that binds to the GH and PRL promoters. It is necessary for emergence and mature function of somatotrophs, lactotropes, and thyrotrophs. Dominant and recessive mutations in POU1F1 are responsible for complete deficiencies of GH and PRL and variable TSH deficiency. Affected individuals exhibit nearly normal fetal growth but experience severe growth failure in the first year of life. With normal production of LH, and FSH, puberty develops spontaneously, though at a later than normal age. Blueprint in Pediatric Endocrinology 265

These patients are not at risk for development of ACTH deficiency. Anterior pituitary size is normal to small. Severe early-onset MPHD including deficiency of ACTH is often associated with the triad of anterior pituitary hypoplasia, absence or attenuation of the pituitary stalk, and an ectopic posterior pituitary bright spot on MRI. Most cases are sporadic; there is a male predominance. Some are due to abnormalities of the SOX3 gene, located on the X chromosome. The majority of cases have not been explained at the genetic level. Pituitary hypoplasia can occur as an isolated phenomenon or in association with more extensive developmental abnormalities such as anencephaly or holoprosencephaly. Midfacial anomalies (cleft lip, palate) or the finding of a solitary maxillary central incisor indicates a high likelihood of GH or other anterior/posterior hormone deficiency. In the Hall-Pallister syndrome, absence of the pituitary gland is associated with hypothalamic hamartoblastoma, postaxial polydactyly, nail dysplasia, bifid epiglottis, imperforate anus, and anomalies of the heart, lungs, and kidneys. Hypopituitarism in Neonates Neonates usually have normal or even high birth weights and lengths and no history of intrauterine growth retardation. Neonates (particularly those with MPHD) often have histories of breech presentation, although the explanation for this is unclear. Hypoglycemia risk is higher with various manifesting symptoms including lethargy, jitteriness, pallor, cyanosis, apnea, or convulsions. Jaundice may be secondary to indirect hyperbilirubinemia (as occurs in thyroid stimulating hormone axis deficiency) or to direct hyperbilirubinemia (as occurs in growth hormone or adrenocorticotropic hormone axis deficiencies). Neonates with hypopituitarism may have undergone several evaluations to exclude sepsis or for unexplained apnea, hypotension, or temperature instability. Consider hypopituitarism as a possible diagnosis when these conditions occur in a full-term infant. Electrolyte disturbances including both hyponatraemia and hypernatremia can occur. Hyponatraemia unassociated with hypovolemia and unresponsive to fluid restriction occurs in infants with hypopituitarism. In contrast to the hyponatraemia that occurs with the salt-losing crisis of 21-hydroxylase deficiency, serum potassium levels are typically low or within the reference range. The hyponatraemia resolves with physiologic corticosteroid replacement. 266 Chapter 7: The Pituitary Gland

Finally, microgenitalia, mainly in males, may result from a gonadotropin deficiency or from GH deficiency. Hypopituitarism in Older Infants & Children Growth failure may be the most common presenting symptom in this age group, possibly with an associated delay in tooth development. Children with acquired or milder forms of gonadotropin deficiency who do not present with microgenitalia in infancy may present later with absent or delayed puberty. Central diabetes insipidus secondary to Antidiuretic hormone (ADH) deficiency presents with symptoms of polyuria and polydipsia are more readily obvious in older children. Children with hypothyroidism secondary to TSH deficiency present with signs and symptoms identical to those of primary hypothyroidism, although typically less severe. These include fatigue, cold intolerance, constipation, dry skin, slow growth, and weight gain but they never have a goiter comparing to primary hypothyroidism. Acquired Causes Any lesion that damages the hypothalamus, pituitary stalk, or anterior pituitary may cause pituitary hormone deficiency. Because such lesions are not selective, multiple hormonal deficiencies are usually observed. The most common lesion is the craniopharyngioma. Central nervous system germinoma, eosinophilic granuloma (histiocytosis), tuberculosis, sarcoidosis, toxoplasmosis, meningitis, and aneurysms may also cause hypothalamic-hypophyseal destruction. Trauma, including shaken child syndrome, motor vehicle crash, traction at delivery, anoxia, and hemorrhagic infarction, may also damage the pituitary, its stalk, or the hypothalamus. Clinical Manifestations Congenital Hypopituitarism The child with hypopituitarism is usually of normal size and weight at birth although those with MPHD and genetic defects of the GH1 or GHR gene have birth lengths that average 1 SD below the mean. Children with severe defects in GH production or action are more than 4 SD below the mean by 1 yr of age. Those with less severe deficiencies grow at rates below the 25% for age and gradually diverge from normal height percentiles. Delayed closure of the epiphyses permits growth Blueprint in Pediatric Endocrinology 267

beyond the normal age when growth should be complete. Infants with congenital defects of the pituitary or hypothalamus usually present with neonatal emergencies such as apnea, cyanosis, or severe hypoglycemia with or without seizures. Microphallus in boys provides an additional diagnostic clue. Deficiency of GH may be accompanied by hypoadrenalism and hypothyroidism. Prolonged neonatal jaundice is common. It involves elevation of conjugated and unconjugated bilirubin and may be mistaken for neonatal hepatitis.

Fig. (7-4): Showing clinical features of congenital hypopituiterism The head in the toddler is round, and the face is short and broad. The frontal bone is prominent, and the bridge of the nose is depressed and saddle-shaped. The nose is small, and the nasolabial folds are well developed. The eyes are somewhat bulging. The mandible and the chin are underdeveloped, and the teeth, which erupt late, are frequently crowded. The neck is short, and the larynx is small. The voice is high- pitched and remains high after puberty. The extremities are well proportioned, with small hands and feet. Weight for height is usually normal, but an excess of body fat and a deficiency of muscle mass contributes to a pudgy appearance. The genitals are usually small for age, and sexual maturation may be delayed or absent. Facial, axillary, and pubic hair usually is lacking, and the scalp hair is fine. Mainly length is affected, giving toddlers a pudgy appearance. Symptomatic hypoglycemia, usually after fasting, occurs in 10–15% of children with panhypopituitarism and those with idiopathic growth hormone deficiency (IGHD). Intelligence is usually normal. 268 Chapter 7: The Pituitary Gland

Growth Hormone Deficiency Growth hormone deficiency can be either isolated or combined with other pituitary hormone deficiencies. Isolated Growth Hormone Deficiency (IGHD) The incidence of IGHD is estimated to be 1 in 3500 to 1 in 10,000 live births. In the vast majority of these patients the cause is unknown and is classified as idiopathic. However, genetic mutations in GH1 and GHRHR are responsible for four distinct forms of familial IGHD (Table1). Table (7-1): Showing Various Genetic Mutations of GH.

IGHD type Inheritance Mutation Phenotype

Autosomal Sever short stature, antibodies Type 1A GH1 Recessive during GH treatment

Autosomal GH1, Short stature, good response to Type 1B Recessive GHRHR GH treatment

Autosomal Short stature, good response to Type II GH1 Dominant GH treatment

Short stature, Type III X-Linked BTK hypogammaglobulinemia

Combined Growth Hormone Deficiency (CGHD) Combined growth hormone deficiency is a combination of two or more pituitary hormone deficiencies. Hypothyroidism, hypocortisolism, hypogonadism and hypoprolactinemia can occur in an isolated form, but often appear in combinations and in most cases, GHD is also present. In contrast to IGHD, CGHD is often accompanied by pituitary gland abnormalities on MRI, such as hypoplasia of the anterior pituitary, and ectopic location of the posterior pituitary or an invisible stalk. When all three abnormalities are present, this is called the ‗‘classic triad‘‘ of pituitary anomalies. In CGHD, the etiology is often unknown; however, several hypotheses related to the pathogenesis of idiopathic hypopituitarism can be dividing into two groups. The embryo- genetic hypothesis, according to which a genetic defect or a defect during Blueprint in Pediatric Endocrinology 269

embryonic organogenesis has lead to an abnormal pituitary. The other hypothesis is the birth trauma hypothesis, in which a traumatic (breech) delivery is thought to have damaged the pituitary. Acquired Hypopituitarism The child initially is normal; manifestations similar to those seen in idiopathic pituitary growth failure gradually appear and progress. When complete or almost complete destruction of the pituitary gland occurs, signs of pituitary insufficiency are present. Atrophy of the adrenal cortex, thyroid, and gonads results in loss of weight, asthenia, sensitivity to cold, mental torpor, and absence of sweating. Sexual maturation fails to take place or regresses if already present. There may be atrophy of the gonads and genital tract with amenorrhea and loss of pubic and axillary hair. There is a tendency to hypoglycemia. Growth slows dramatically. Diabetes insipidus may be present early but tends to improve spontaneously as the anterior pituitary is progressively destroyed. If the lesion is an expanding tumor, symptoms such as headache, vomiting, visual disturbances, pathologic sleep patterns, decreased school performance, seizures, polyuria, and growth failure may occur. Slowing of growth may antedate neurologic signs and symptoms, especially with craniopharyngioma, but symptoms of hormonal deficit account for only 10% of presenting complaints. Evidence of pituitary insufficiency may first appear after surgical intervention. In children with Craniopharyngioma, visual field defects, optic atrophy, papilledema, and cranial nerve palsy are common. Diagnosis of Hypopituitarism Corticotrophin Deficiency Basal ACTH levels are secreted episodically, resulting in wide fluctuations in serum plasma levels. In evaluating ACTH deficiency, serum cortisol levels should be measured at 8 to 9 AM. Plasma cortisol levels must be interpreted carefully, because there is considerable overlap between cortisol insufficiency and normal cortisol secretion. Provocative testing to evaluate ACTH reserve is indicated when suspicion of or risk for hypocortisolism is present. Direct evaluation of the ACTH reserve can be performed by means of several provocative tests, including the metyrapone, insulin-induced hypoglycemia, and Synacthen stimulation tests. 270 Chapter 7: The Pituitary Gland

The administration of metyrapone is one of several provocative tests to assess the ACTH reserve. Overnight metyrapone test is by giving metyrapone, 30 mg/kg orally, administered at midnight, Metyrapone blocks 11-β-hydroxylase, an enzyme that catalyzes the final step in cortisol biosynthesis. The decrease in cortisol secretion after metyrapone is given should result in a compensatory increase in the ACTH level. The precursor 11-deoxycortisol level should also increase if the hypothalamic-pituitary-adrenal axis is normal. Insulin-induced Hypoglycemia Test Insulin-induced hypoglycemia evokes a stress-mediated activation of the hypothalamic-pituitary-adrenal axis to stimulate ACTH and cortisol secretion. Insulin (0.1 U/kg body weight) is administered. The blood sugar level should fall to lower than 40 mg/dl, with symptoms of diaphoresis, tachycardia, weakness, and headache. Serum glucose and cortisol concentrations should be measured before testing and then five incremental measurements of serum glucose and cortisol concentration should be done over 2 hours. Synacthen (Cosyntropin) Stimulation Test Assessment of the plasma cortisol response to synthetic ACTH is known as the synacthen stimulation test. Cosyntropin (synthetic ACTH) 250 μg is administered intramuscularly or intravenously. The 1-μg synacthen stimulation test (intravenous only) may be more sensitive for the diagnosis of subtle secondary adrenal insufficiency. Thyrotropin Deficiency Clinically hypothyroid patients with known hypothalamic-pituitary dysfunction may have a normal serum TSH level but inadequate thyrotropin secretion. When pituitary dysfunction is suspected, the serum TSH concentration alone cannot be used for the assessment of adequate pituitary thyrotropin secretion, but must be used in conjunction with the serum TSH concentration for this assessment. Gonadotropin Deficiency In males, assessment of the serum testosterone concentration level is a sensitive indicator of LH deficiency when a pituitary dysfunction is known. Serum testosterone concentration should be measured between 8 and 10 AM. A low concentration should be confirmed with a second Blueprint in Pediatric Endocrinology 271

serum sample. A subnormal serum testosterone level with a normal or subnormal LH concentration is indicative of secondary hypogonadism. Primary hypogonadism manifests with elevated LH and subnormal testosterone levels. In females, LH and FSH levels with a low serum estradiol level suggest hypothalamic-pituitary dysfunction or secondary gonadal failure. Elevated levels of LH and FSH in the presence of hypoestrogenism suggest primary ovarian failure. Growth Hormone Deficiency In patients with known pituitary disease and deficiencies of ACTH, TSH, and gonadotropin, there is a 95% chance of the presence of a subnormal provocative stimulus for growth hormone. Also, patients with known pituitary disease and a serum IGF-1 concentration lower than normal can be presumed to have growth hormone deficiency. Provocative tests for growth hormone deficiency include the insulin- induced hypoglycemia, growth hormone–releasing hormone (GHRH), clonidine, L-Arginine, glucagon and levodopa-tests. Insulin-induced hypoglycemia is a powerful stimulus of growth hormone release. In a patient who has organic pituitary disease, growth hormone will fail to increase normally (should increase to at least 10 ng/ml) after adequate hypoglycemia has been achieved. Similarly, the combination of arginine and GHRH is a potent stimulus of growth hormone release. A dose of GHRH (1 μg/kg) combined with an infusion of arginine (0.5 g/kg up to 30 g maximum) should stimulate a release of GH. Radiologic Findings in MPHD Conventional x-ray films of the skull have been replaced by computed tomography and, increasingly, by magnetic resonance imaging. CT is appropriate for recognizing suprasellar calcification associated with Craniopharyngioma and bony erosions accompanying histiocytosis. MRI provides a much more detailed view of hypothalamic and pituitary anatomy. Many cases of severe early-onset MPHD show the triad of a small anterior pituitary gland, a missing or attenuated pituitary stalk, and an ectopic posterior pituitary bright spot at the base of the hypothalamus. Subnormal anterior pituitary height, implying a small anterior pituitary, is common in genetic and idiopathic causes of IGHD. Craniopharyngioma is common and pituitary adenomas are rare in children with hypopituitarism. Both hypoplastic and markedly enlarged 272 Chapter 7: The Pituitary Gland

anterior pituitary glands are seen in patients with PROP1 or LHX3 mutations. Skeletal maturation is delayed in patients with IGHD and may be even more delayed when there is combined GH and TSH deficiency. Dual photon x-ray absorptiometry shows deficient bone mineralization, deficiencies in lean body mass, and a corresponding increase in adiposity. Treatment of Various MPHD GH Deficiency Children requiring treatment usually receive daily injections of growth hormone. Pediatric endocrinologists monitor growth and adjust dose every 3 to 6 months Treatment is usually extended as long as the child is growing, and lifelong continuation may be recommended for those most severely deficient. Nearly painless insulin syringes, pen injectors, or a needle-free delivery system reduce the discomfort. Injection sites include the biceps, thigh, buttocks, and stomach. Injection sites should be rotated daily to avoid lipoatrophy. GH treatment is very expensive, so it's important to discuss this issue with the family of the patient. Adrenocorticotropic Hormone Deficiency Hydrocortisone replacement should be given orally as 8-12 mg/m2/day divided into two - three daily doses. Ideally, two thirds of the total daily dose should be given in the morning and afternoon and one third of the daily dose should be given in the evening. This regimen most closely mimics normal physiology Alternative, dexamethasone or prednisone can be used for glucocorticoid replacement. Prednisone is given at a total daily dosage of 5 to 7.5 mg/m2 in one to two doses. Dexamethasone is given at 0.03 to 0.15 mg/kg/day. Some authorities prefer these alternatives because of their longer drug half-life (preferably after closure of bone epiphysis). A two- to threefold increase in glucocorticoid dosage should be used in stress situations and then tapered to the maintenance dose. Those with secondary adrenal insufficiency should not require mineralocorticoid replacement because aldosterone secretion is not dependent on ACTH secretion. They should be advised to wear a medical alert bracelet so that appropriate treatment is given in emergency situations. Blueprint in Pediatric Endocrinology 273

Thyroid-Stimulating Hormone Deficiency Levothyroxine is the treatment for TSH deficiency. A typical replacement dose in children is 100 μg/ m2/ day. The goal of therapy is to achieve a normal serum thyroxin level and clinical euthyroidism. Serum free T4 levels should be in the middle to upper normal range. TSH cannot be used to assess adequacy of treatment in cases of secondary or tertiary hypothyroidism. . Thyroid replacement will increase the clearance of cortisol. . Those with hypopituitarism should be assessed for ACTH deficiency; glucocorticoid replacement is indicated before thyroid hormone is replaced. . This will avoid creating potentially life-threatening hypotension secondary to subnormal serum cortisol secretion. Luteinizing Hormone and Follicle-stimulating Hormone Deficiency Estradiol and progesterone replacement is the treatment of choice for secondary hypogonadism. A wide variety of estrogen preparations are available for replacement. Conjugated estrogen of 0.625 mg daily, ethinyl estradiol of 1 mg daily, estradiol patches of 0.05 mg changed twice weekly are available options. If the uterus has not been removed, progesterone should be added to induce withdrawal bleeding and prevent endometrial hyperplasia. This can be added as Medroxyprogestrone 5 to 10 mg daily for the last 10 days of each month. Testosterone cypionate, 50 to 100 mg, administered intramuscularly every 4 weeks in males. Anti-Diuretic Hormone Physiology of Water Balance The control of extracellular tonicity (osmolality) and volume within a narrow range is critical for normal cellular structure and function. Extracellular fluid tonicity is regulated almost exclusively by water intake and excretion, whereas extracellular volume is regulated by sodium intake and excretion. The control of plasma tonicity and intravascular volume involves a complex integration of endocrine, neural, behavioral, and paracrine systems. Vasopressin, secreted from the posterior pituitary, is the principal regulator of tonicity, with its release 274 Chapter 7: The Pituitary Gland

largely stimulated by increases in plasma tonicity. Volume homeostasis is largely regulated by the renin-angiotensin-aldosterone system, with contributions from both vasopressin and the natriuretic peptide family. Vasopressin, a 9-amino-acid peptide, has both Antidiuretic and vascular pressor activity and is synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. It is transported to the posterior pituitary via axonal projections, where it is stored awaiting release into the systemic circulation. The half-life of vasopressin in the circulation is 5 minutes. In addition to responding to osmotic stimuli, vasopressin is secreted in response to significant decreases in intravascular volume and pressure (minimum of 8% decrement) via afferent baroreceptors pathways arising from the aortic arch (carotid sinus) and volume receptor pathways in the cardiac atria and pulmonary veins. Osmotic and hemodynamic stimuli interact synergistically. The sensation of thirst is regulated by cortical as well as hypothalamic neurons. The thirst threshold is approximately 10 mOsm/kg higher (~295 mOsm/kg) than the osmotic threshold for vasopressin release. Therefore, under conditions of hyperosmolality, vasopressin is released prior to the initiation of thirst, allowing for retention of ingested water. Chemoreceptors present in the oropharynx rapidly down-regulate vasopressin release following water ingestion. Vasopressin exerts its principal effect on the kidney via V2 receptors located primarily in the collecting tubule, the thick ascending limb of the loop of Henle, and the peri-glomerular tubules. The human V2 receptor gene is located on the long arm of the X chromosome (Xq28) at the locus associated with congenital, X-linked, vasopressin-resistant diabetes insipidus. Activation of the V2 receptor results in increases in intracellular cyclic adenosine monophosphate, which leads to the insertion of the aquaporin-2 water channel into the apical (luminal) membrane. This allows water movement along its osmotic gradient into the hypertonic inner medullary interstitium from the tubule lumen and excretion of concentrated urine. In contrast to aquaporin-2, aquaporins-3 and -4 are expressed on the basolateral membrane of the collecting duct cells and aquaporin-1 is expressed in the proximal tubule. These channels may also contribute to urinary concentrating ability. Blueprint in Pediatric Endocrinology 275

Atrial natriuretic peptide (ANP), initially isolated from cardiac atrial muscle, has a number of important effects on salt and water balance, including stimulation of natriuresis, inhibition of sodium resorption, and inhibition of vasopressin secretion. ANP is expressed in endothelial cells and vascular smooth muscle, where it appears to regulate relaxation of arterial smooth muscle. ANP is also expressed in the brain, along with other natriuretic family members; the physiologic role of these factors has yet to be defined. Approach to The Patient With Polyuria, Polydipsia, and Hypernatremia The cause of pathological polyuria or polydipsia (exceeding 2 L/m2/day) may be difficult to establish in children. Infants may present with irritability, failure to thrive, and intermittent fever. Patients with suspected DI should have a careful history taken, which should quantify the child's daily fluid intake and output and establish the voiding pattern, nocturia, and primary or secondary enuresis. A complete physical examination should establish the patient's hydration status, and the physician should search for evidence of visual and central nervous system dysfunction as well as other pituitary hormone deficiencies. The diagnosis of DI is established if the serum osmolality is greater than 300 mOsm /kg and the urine osmolality is less than 600 mOsm/kg. DI is unlikely if the serum osmolality is less than 270 mOsm/kg or the urine osmolality is greater than 600 mOsm/kg. If the patient's serum osmolality is less than 300 mOsm/kg (greater than 270 mOsm/kg) and pathologic polyuria and polydipsia are present, a water deprivation test is indicated to establish the diagnosis of DI and to differentiate central from nephrogenic causes. Central Diabetes Insipidus Central diabetes insipidus can result from multiple etiologies, including genetic mutations in the vasopressin gene; trauma (accidental or surgical) to vasopressin neurons; congenital malformations of the hypothalamus or pituitary neoplasm; infiltrative, autoimmune, and infectious diseases affecting vasopressin neurons. In approximately 10% of children with central DI, the etiology is idiopathic. Other pituitary hormone deficiencies may be present. Autosomal dominant central DI usually presents within the first 5 years of life and results from mutations 276 Chapter 7: The Pituitary Gland

in the vasopressin gene. A number of mutations can cause gene- processing defects in a subset of vasopressin-expressing neurons. Wolfram syndrome, which includes diabetes insipidus, diabetes mellitus, optic atrophy, and deafness, also results in vasopressin deficiency. The gene for this disorder has been identified, but its function is unknown. Congenital brain abnormalities such as septo-optic dysplasia with agenesis of the corpus callosum, holoprosencephaly, and familial pituitary hypoplasia with absent stalk may be associated with central DI and defects in thirst perception. Empty sella syndrome, possibly due to unrecognized pituitary infarction, can be associated with DI in children. Trauma (to the base of the brain) and neurosurgical intervention (in the region of the hypothalamus or pituitary) are common causes of central DI. The triphasic response following surgery refers to an initial phase of transient DI, lasting 12–48 hour, followed by a second phase of syndrome of inappropriate Antidiuretic hormone secretion, lasting up to 10 days, which may be followed by permanent DI. The initial phase may be the result of local edema interfering with normal vasopressin secretion; the second phase results from unregulated vasopressin release from dying neurons, whereas in the third phase, permanent DI results if more than 90% of the neurons have been destroyed. Given the anatomic distribution of vasopressin neurons over a large area within the hypothalamus, tumors that cause DI must either be very large and infiltrative or be strategically located near the base of the hypothalamus, where vasopressin axons converge before their entry into the posterior pituitary. Germinoma and pinealoma typically arise in this region and are among the most common primary brain tumors associated with DI. Germinoma can be very small and undetectable by MRI for several years following the onset of polyuria. Quantitative measurement of the β– subunit of human chorionic gonadotropin, often secreted by germinoma and pinealoma, should be performed in children with idiopathic or unexplained DI in addition to serial MRI scans. Craniopharyngioma and optic glioma can also cause central DI when very large, although this is more often a postoperative complication of the treatment for these tumors. Hematological malignancies, as with acute myelocytic leukemia, can cause DI via infiltration of the pituitary stalk and sella. Langerhans cell histiocytosis and lymphocytic hypophysitis are common types of infiltrative disorders causing central DI, with hypophysitis as the cause in 50% of cases of ―idiopathic‖ central DI. Blueprint in Pediatric Endocrinology 277

Infections involving the base of the brain, including meningitis (meningococcal, cryptococcal, listerial, and toxoplasmal), congenital cytomegalovirus infection, and nonspecific inflammatory diseases of the brain may give rise to central DI that is often transient. Drugs associated with the inhibition of vasopressin release include ethanol, phenytoin, opiate antagonists, halothane, and α-adrenergic agents. Nephrogenic Diabetes Insipidus (NDI) NDI can result from genetic or acquired causes. Genetic causes are less common but more severe than acquired forms of NDI. The polyuria and polydipsia associated with genetic NDI usually presents within the first several wk of life but may only become apparent after weaning or with longer periods of nighttime sleep. Many infants initially present with fever, vomiting, and dehydration. Failure to thrive may be secondary to the ingestion of large amounts of water, resulting in caloric malnutrition. Long-standing ingestion and excretion of large volumes of water may lead to nonobstructive hydronephrosis, hydroureter, and megabladder. Congenital X-linked NDI results from inactivating mutations of the vasopressin V2 receptor. Congenital autosomal recessive NDI results from defects in the aquaporin-2 gene. An autosomal dominant form of NDI is associated with processing mutations of the aquaporin-2 gene. Acquired nephrogenic DI may result from hypercalcemia or hypokalemia and is associated with drugs including, lithium, demeclocycline, foscarnet, clozapine, amphotericin, methicillin, and rifampin. Impaired renal concentrating ability can also be seen with ureteral obstruction, chronic renal failure, polycystic kidney disease, medullary cystic disease, Sjogren syndrome, and sickle cell disease. Decreased protein or sodium intake or excessive water intake, as in primary polydipsia, can lead to diminished tonicity of the renal medullary interstitium and nephrogenic DI. Water Deprivation Test Interpretation The test can be properly interpreted only if plasma osmolality greater than 290 mosmol /L is reached. At lower levels, ADH secretion is not maximally stimulated, urine may not be concentrated, and a response to pitressin may be present. Central diabetes insipidus is diagnosed when plasma osmolality is elevated, urine osmolality is low and there is a 278 Chapter 7: The Pituitary Gland

significant response to pitressin. In nephrogenic DI, there is no response to pitressin. In subjects without DI, urine volume drops and urine osmolality increases usually to at least twice to three times plasma osmolality (age-dependent). Serum osmolality does not rise significantly. Plasma ADH levels rise. In subjects with ADH deficiency (central DI), urine losses continue and dehydration ensues, plasma osmolality increases, with no or little rise in urine osmolality. In partial DI, urine osmolality may rise to a peak of 300 - 600 mosm/l. ADH rise may be poor, but this is not diagnostic. Administration of DDAVP leads to urinary concentration. In nephrogenic DI, findings are similar to ADH deficiency, except there is no or poor response to DDAVP administration, and ADH levels are usually clearly elevated. Treatment of Central Diabetes Insipidus Fluid Therapy With an intact thirst mechanism and free access to oral fluids, a person with complete DI can maintain plasma osmolality and sodium in the high normal range, although at great inconvenience. Neonates and young infants are often best treated solely with fluid therapy, given their requirement for large volumes (3 L/m2/day) of nutritive fluid. The use of vasopressin analogs in patients with obligate high fluid intake is contraindicated given the risk of life-threatening hyponatraemia. Vasopressin Analogs Treatment of central DI in children is best accomplished with the use of the long-acting vasopressin analog dDAVP (desmopressin). DDAVP is available in an intranasal preparation (onset 5–10 min) and as tablets or melt preparations (onset 15–30 min). The intranasal preparation of dDAVP (10 μg/0.1 ml) can be administered by rhinal tube (allowing dose titration) or by nasal spray. The appropriate dose is determined empirically based on the desired length of antidiuresis. The nasal spray delivers 10 μg (0.1 ml) per spray and is the standard preparation used for treatment of primary enuresis in older children. Use of dDAVP in the treatment of enuresis is a temporizing measure because it does not affect the underlying condition, and it should be used with caution. To prevent water intoxication, patients should have at least 1 hr of urinary breakthrough between doses each day. DDAVP tablets are available but require at least a 10-fold increase in the dose compared with the Blueprint in Pediatric Endocrinology 279

intranasal preparation. Oral doses of 0.2 to 0. 3 mg every 8–12 hour is safe and effective in children. Aqueous Vasopressin Central DI of acute onset following neurosurgery is best managed with continuous administration of synthetic aqueous vasopressin (pitressin). Under most circumstances, total fluid intake must be limited to 1 L/m2/24 hr during antidiuresis. A typical dose for intravenous vasopressin therapy is 1.5 mU/kg/hour. Vasopressin concentrations greater than 1,000 pg/ml should be avoided because they may cause cutaneous necrosis, rhabdomyolysis, and cardiac rhythm disturbances. Post-neurosurgical patients treated with vasopressin infusion should be switched from intravenous to oral fluids as soon as possible to allow thirst sensation, if intact, to help regulate osmolality. Treatment of Nephrogenic Diabetes Insipidus (NDI) The treatment of acquired NDI focuses on elimination, if possible, of the underlying secondery causes, e.g. offending drugs, hypercalcemia, hypokalemia, or ureteral obstruction. Congenital nephrogenic diabetes insipidus is often difficult to treat. The main goals are to ensure the intake of adequate calories for growth and to avoid severe dehydration. Pharmacologic approaches to the treatment of NDI include the use of thiazide diuretics and are intended to decrease the overall urine output. Thiazides appear to induce a state of mild volume depletion by enhancing sodium excretion at the expense of water and by causing a decrease in the glomerular filtration rate, which results in proximal tubular sodium and water reabsorption. Indomethacin and amiloride may be used in combination with thiazides to further reduce polyuria. High-dose dDAVP therapy, in combination with indomethacin, has been used in some subjects with NDI. This treatment may prove useful in patients with genetic defects in the V2 receptor associated with a reduced binding affinity for vasopressin. Diabetes Insipidus . General, they have inability to concentrate urine . Infants may present with failure to thrive, vomiting, constipation, unexplained fevers; severe dehydration, hypovolemic shock, and seizure may occur in more severe cases 280 Chapter 7: The Pituitary Gland

. It could be central or nephrogenic . Diagnosis is confirmed by water-deprivation test. Central DI . Caused by vasopressin deficiency, associated with CNS injury, including trauma and tumors. . Following trauma to axons of vasopressin containing neurons, a temporary or permanent DI may result. . Due to the initial edema occurring in the area of the hypothalamus and pituitary, a short-lived period (2–5 days) of DI is observed. This is succeeded by a stage of SIADH, as dying neurons release vasopressin. The final stage results in permanent DI, if a significant number of neurons are injured. . Laboratory findings: Low urine specific gravity (< 1.005), low urine osmolality (50–200), low vasopressin (< 0.5 pg/ml) . Treatment is by intravenous, oral, melt, subcutaneous or nasal desmopressin acetate. . Titrate desmopressin dosage according to urine output; goal is to keep of ≥1 ml/kg/hour period of diuresis per day that stimulates thirst. . Monitor electrolytes. Infants are often not treated with DDAVP due to difficulty monitoring input and output. Rather, they can be treated with increased free water and salt restriction. Nephrogenic DI . It is caused by renal tubular resistance to vasopressin; genetic or acquired. . Low urine specific gravity (< 1.005), low urine osmolality (50– 200 mOsm/L). . Treatment: Increase free water and a low-salt diet Suggested Doses of Desmopressin . Neonates and < 1 year: 1 - 2.5µg Desmopressin intranasally. . Children 1 – 5 years: 2.5 – 5 µg Desmopressin intranasally. . 5 years: 5 – 10µg Desmopressin intranasally. Blueprint in Pediatric Endocrinology 281

. As an alternative, if specified by the consultant, Desmopressin may be administered by injection: dose 0.5 µg/m2 BSA (approximately 10 folds potency of nasal) . New melt preparation is currently available, 60 mcg equal to 0.1 mg tablet and 120 mcg equal to 0.2 mg tablet The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) It is characterized by hypotonic hyponatraemia, concentrated urine, and fluid retension. The impairment of free water excretion is caused by increased arginine vasopressin (AVP) release. Pseudohyponatraemia due to hyperglycemia, hyperlipidemia, or hyperproteinaemia should be ruled out first. Renal failure, adrenal insufficiency, and appropriate release of AVP secondary to extracellular volume depletion (hypovolemia, due to gastrointestinal or renal loss) or intravascular volume depletion (hypervolemia due to congestive heart failure, liver cirrhosis, or nephrotic syndrome), must be ruled out in order to diagnose SIADH. Hypodipsia Thirst and drinking are essential components of normal osmoregulation in healthy children. Abnormalities of thirst appreciation, in particular hypodipsia, have profound implications for water homeostasis. The combination of cranial diabetes insipidus and hypodipsia can have particularly serious consequences, with the potential for life-threatening hypernatremia. The precise neural control of thirst appreciation remains unknown, and perhaps as a result of this, satisfactory therapies for the treatment of disorders of thirst have not yet been developed; behavioral modification and retraining of drinking habits remain the rather limited cornerstones of management. Pathophysiology of SIADH Arginine vasopressin hormone is produced in the hypothalamus and delivered to the posterior pituitary for release into systemic circulation. Secretion of AVP is mediated by several mechanisms. Osmotic pressure is the most sensitive and important stimulus for AVP release and is mediated by osmoreceptors in the hypothalamus. Sodium concentration greatly influences osmotic pressure. A decrease in osmolality, as minimal as 1% to 2%, rapidly suppresses AVP secretion and induces free water diuresis. Arterial pressure reduction also stimulates AVP release, but 282 Chapter 7: The Pituitary Gland

typically there must be a significant reduction of 10% to 20%, as sensed by baroreceptors in the left atrium and aorta. It appears that arterial pressure provokes AVP release by lowering the set point of the osmoregulatory system. Other non-osmotic stimuli for AVP release include stress, nausea, pain, and vasovagal stimulation. AVP exerts its effect by stimulating V2 receptor, located on the basolateral side of the principal cell. These receptors may also be activated by other, currently undiscovered, Antidiuretic substances. AVP V2 is a G-protein-coupled receptor that, when stimulated, initiates adenylate cyclase and leads to increased intracellular cAMP. Elevated cAMP signals placement of vesicle-encased aquaporin-2 channels in the principal cell apical membrane, facilitating free water absorption in the collecting tubule resulting concentrated urine, coupled with free water intake in excess of what can be excreted, leads to hyponatraemia. This is especially true in the case of exercise-associated hyponatraemia, in which excessive water intake is coupled with increased non-osmotic release of AVP through stress and pain. Extracellular volume increases and plasma renin/aldosterone secretion is suppressed to cause a naturesis which further aggravating hyponatraemia. Causes of SIADH . Drugs including amiodarone, carbamazepine, chlorpromazine, amitriptyline, and NSAID. . Pulmonary diseases including pulmonary infections and lung cancers, especially small cell lung cancer. . Malignancy including lung, gastrointestinal, genitourinary cancers; lymphomas; and sarcomas. . CNS disorders including CNS infections, brain trauma, hemorrhage, multiple sclerosis, Guillain-Barre syndrome, and acute intermittent porphyria. . Other stimuli for AVP release: such as anesthesia and postoperative state, nausea, vomiting, pain, and endurance exercise. . Nephrogenic syndrome of inappropriate antidiuresis or pseudo- SIADH is due to gain-of-function mutations in the vasopressin 2 (V2) receptor, which is constitutively active. Blueprint in Pediatric Endocrinology 283

. This initiates aquaporin-2 placement into the apical membrane of cortical collecting duct cells and corresponding free water permeability, in face of appropriately low serum AVP levels. Treatment of SIADH Currently, the mainstay of treatment for SIADH is to remedy hyponatraemia with salt administration and /or water restriction. The inappropriate activation of the V2-receptor, causing excessive free water absorption in the collecting duct, has been recently targeted with the introduction of the vasopressin receptor antagonists. Acute Hyponatraemia ( < 48 hours' duration) First and foremost, patients are evaluated for severe symptoms of hyponatraemia (mental status changes, seizure, and coma). As this is not of chronic duration, brain cells have not had time to compensate by releasing electrolytes and brain osmolytes. Therefore, patients with acute hyponatraemia are more susceptible to symptoms at higher serum sodium levels. Intravenous hypertonic saline (3% sodium chloride solution) is administered and serum sodium levels checked every 2 hours, with a goal of increasing serum sodium by 1 - 2 mmol/L/hour until neurological symptoms resolve. Subsequently, correction is slowed to elevate serum sodium by no more than 8 - 10 mmol/l in a 24-hour period thereafter. There is less risk of central pontine myelinolysis (osmotic demyelination syndrome) in patients who develop hyponatraemia in < 48 hours as compared with those with chronic hyponatraemia. Therefore, more rapid correction, although not ideal, is less dangerous in patients with acute hyponatraemia. Furosemide may be used in addition to hypertonic saline, especially if the patient is at risk for volume overload. Furosemide helps to correct hyponatraemia by increasing free water excretion. If Furosemide is used in addition to intravenous hypertonic saline, infusion rates may need to be reduced, so as to avoid overcorrection of hyponatraemia. Hypokalemia is monitored and corrected with intravenous potassium replacement. Acute hyponatraemia may be self-limited. It may be necessary to continue free fluid restriction after hypertonic saline therapy is discontinued. Serum sodium is monitored daily until it stabilizes. 284 Chapter 7: The Pituitary Gland

Chronic Hyponatraemia (> 48 hours or unknown duration) with Severe neurological Symptoms, Serum sodium < 125 mmole/L These patients are also treated with intravenous hypertonic saline. There is an increased risk of central pontine myelinolysis (CPM, osmotic demyelination syndrome) in chronically hyponatraemic patients, so careful monitoring is of utmost importance. Central pontine myelinolysis occurs with overcorrection of hyponatraemia where solute-poor cerebral cells are subject to shrinkage. It is characterized by demyelination of pontine, basal ganglion, and cerebellar regions, with resultant neurological symptoms, including behavior disturbances, lethargy, dysarthria, dysphagia, paraparesis or quadriparesis, and coma. Seizures may also be seen but are less common. Malnutrition, potassium depletion, and hepatic failure increase the risk of development of central pontine myelinolysis. Furosemide may also be used in addition to hypertonic saline, especially if the patient is at risk for volume overload, and hypokalemia is corrected if necessary with IV potassium replacement. Following successful therapy with IV hypertonic saline, a vasopressin receptor antagonist (vaptan) is used. Vasopressin receptor antagonists (vaptans) compete with argininevasopressin (AVP) for binding at the V2 receptor on the basolateral side of the principal cell and inhibit water channel insertion and free water absorption. Conivaptan is a non-selective vasopressin receptor antagonist that affects both V1 and V2 receptors. This drug was approved in 2005 by the US FDA, and is currently available in the intravenous form for inpatient administration only. . The oral vasopressin receptor antagonist tolvaptan was approved in 2008 for the treatment of worsening heart failure and hyponatraemia. . It was approved by the FDA for hyponatraemia associated with SIADH, heart failure, and cirrhosis of the liver Close monitoring, especially in the first 24 hours of oral therapy, is required. The concern is overcorrection of serum sodium (>12 mmole / day), that occasionally occurs with these medicines. Fluid restriction should be removed, because polyuria commonly occurs. Long-term studies have been promising in terms of sustained improved serum sodium with these agents. Vasopressin receptor antagonists interact with Blueprint in Pediatric Endocrinology 285

the cytochrome P450 3A4 system and use with other potent inhibitors is contraindicated. Persistent Chronic SIADH SIADH can persist if the underlying cause is irreversible. Fluid restriction of 1 to 1.5 L/day has been the mainstay of therapy for chronic SIADH outpatient therapy. Compliance with fluid restriction often limits this therapeutic option. If patients are intolerant to fluid restriction, tolvaptan and demeclocycline may be used. Tolvaptan has demonstrated to be well tolerated with most commonly reported side effects of dry mouth, thirst, and polyuria coinciding with the mechanism of action of the medication. High cost may limit the use of tolvaptan. Demeclocycline, a bacteriostatic antibiotic, causes diminished responsiveness of the collecting tubule to AVP. Similar to tolvaptan, demeclocycline is used without fluid restriction. Side effects such as skin photosensitivity and nephrotoxicity limit its use. Complications Central pontine myelinolysis (Osmotic Demyelination Syndrome) Occurs in people with longstanding SIADH who undergo over aggressive treatment of hyponatraemia. The brain adapts slowly to hyponatraemia by secretion of intracellular solutes such as sodium and potassium initially, followed by amino acids and myoinositol (organic osmolytes). Overcorrection of hyponatraemia can subject solute-poor cerebral cells to shrinkage and CPM. CPM is characterized by demyelination of pontine, basal ganglion, and cerebellar regions with resultant neurological symptoms, including behavior disturbances, lethargy, dysarthria, dysphagia, paraparesis or quadriparesis, and coma. Seizures may also be seen, but are less common. Malnutrition, potassium depletion, and hepatic failure increase the risk of development of CPM. CPM occurs more frequently in longstanding SIADH, due to brain adaptation to hyponatraemia. It can also occur in acute SIADH (duration <48 hours), but this is less likely. To treat overcorrection of hyponatraemia (either as a result of aggressive salt administration or spontaneous water diuresis after offending medicines are discontinued), free water is repleted through increased oral intake or hypotonic fluids.

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Cerebral Salt wasting Syndrome (CSWS) Rare condition composed of hyponatraemia, polyuria and dehydration. The hyponatraemia is due to excessive renal sodium excretion resulting from a centrally mediated process. The condition was initially described in 1950. CSWS is usually caused by brain injury/trauma or cerebral lesion, tumor, or hematoma. CSWS is a diagnosis of exclusion and may be difficult to distinguish from the syndrome of inappropriate Antidiuretic hormone , which develops under similar circumstances and also presents with hyponatraemia. The main clinical difference is that of total fluid status of the patient. CSWS leads to a relative or overt hypovolemia whereas SIADH is consistent with a normal to hypervolemia range. Random urine sodium concentrations tend to be lower than 100 mEq /L in CSWS and greater in SIADH. If blood-sodium levels increase when fluids are restricted, SIADH is more likely. Treatment While CSWS usually appears within the first week after brain injury and spontaneously resolves in 2–4 weeks, it can sometimes last for months or years. While fluid restriction is used to treat SIADH, CSWS requires aggressive hydration and correction of the low sodium levels using sodium chloride tablets. Sometimes, usage of fludrocortisone improves the hyponatraemia, characteristics of CSWS. Hyperpituitarism Primary hypersecretion of pituitary hormones occurs rarely in children. When it does, it usually occurs as a result of a pituitary adenoma. Primary hyperpituitarism should not be confused with secondary hyperpituitarism, which occurs in the setting of target hormone deficiencies resulting in decreased hormonal feedback, such as in hypogonadism, hypoadrenalism, or hypothyroidism. In some cases, long-standing hormonal hypersecretion is accompanied by sufficient hyperplasia of the pituitary to produce sellar enlargement, erosion, and rarely, increased intracranial pressure. The elevated pituitary hormone levels readily suppress to normal following replacement of end-organ hormones. Pituitary hyperplasia can also occur in response to stimulation by ectopic production of releasing hormones such as that seen occasionally in patients with Cushing syndrome secondary to Blueprint in Pediatric Endocrinology 287

corticotrophin-releasing hormone excess or in children with acromegaly secondary to growth hormone–releasing hormone (GHRH) produced by a variety of systemic tumors. The most frequently seen adenoma during childhood is the prolactinoma, followed by corticotropinoma and then somatotropinoma, which secrete prolactin, corticotrophin, and growth hormone, respectively. There have been several case reports of thyrotropinoma in children. There are no pediatric reports of gonadotropinoma. The monoclonal nature of most pituitary adenomas has implied that most originate from a clonal event in a single cell. It is suspected that some pituitary tumors may result from stimulation with hypothalamic-releasing hormones and in other instances, as in McCune-Albright syndrome, the tumor is caused by constitutive activating mutation of the G-protein Gsα gene. The clinical presentation typically depends on the pituitary hormone that is hypersecreted. Disruption of growth regulation and/or sexual maturation is common, as a result of either hormone hypersecretion or local compression by the tumor. Excess Growth Hormone Secretion and Pituitary Gigantism In young persons with open epiphyses, overproduction of GH results in gigantism; while in persons with closed epiphyses, the result is acromegaly. Often, some acromegalic features are seen with gigantism, even in children and adolescents. After closure of the epiphyses, the acromegalic features become more prominent. Pituitary gigantism is rare, and its cause is most often a pituitary adenoma, but gigantism has been observed in a 2.5 year old boy with a hypothalamic tumor that presumably secreted GHRH. Other tumors, for example those that are part of the MEN syndromes, particularly in the pancreas, have produced acromegaly by secretion of large amounts of GHRH with resultant hyperplasia of the somatotrophs. The cardinal clinical feature of gigantism is longitudinal growth acceleration secondary to GH excess. The usual manifestations consist of coarse facial features and enlarging hands and feet. In young children, rapid growth of the head may precede linear growth. Some patients have behavioral and visual problems. Acromegalic features consist chiefly of enlargement of the distal parts of the body, but manifestations of abnormal growth involve all portions. The circumference of the skull increases, the nose 288 Chapter 7: The Pituitary Gland

becomes broad, and the tongue is often enlarged, with coarsening of the facial features. The mandible grows excessively, and the teeth become separated. Visual field defects and neurologic abnormalities are common; signs of increased intracranial pressure appear later. The fingers and toes grow chiefly in thickness. There may be dorsal kyphosis. Fatigue and lassitude are early symptoms. GH levels are elevated and may occasionally exceed 100 ng/ml. There is usually no suppression of GH levels by the hyperglycemia of a glucose tolerance test. IGF-1 and IGFBP-3 levels are consistently elevated in acromegaly, whereas other growth factors are not. Gigantism is rare, with only several hundred reported cases to date. The presentation of gigantism is usually dramatic, unlike the insidious onset of acromegaly in adults. The tumor mass itself may cause headaches, visual changes due to optic nerve compression, and hypopituitarism. GH secreting tumors are typically eosinophilic or chromophobe adenomas. Adenomas may compromise other anterior pituitary function through growth or cystic degeneration. Secretion of gonadotropin, thyrotropin, or corticotrophin may be impaired. Delayed sexual maturation or hypogonadism may occur. When GH hypersecretion is accompanied by gonadotropin deficiency, accelerated linear growth may persist for decades. In some cases, the tumor spreads outside the sella, invading the sphenoid bone, optic nerves, and brain. GH-secreting tumors in pediatric patients are more likely to be locally invasive or aggressive than are those in adults. Gigantism may result from mutations that generate constitutively activated G-proteins with reduced GTPase activity. The resultant increase in intracellular cyclic adenosine monophosphate in the pituitary leads to increased GH secretion. McCune-Albright syndrome (MAS), which can also be caused by mutations resulting in constitutively activated G- proteins, may also include the presence of somatotrophic tumors and excess GH secretion. Approximately 20% of patients with gigantism are those with MAS (commonly consisting of a triad of precocious puberty, cafe-au-lait spots, and fibrous dysplasia). GH-secreting tumors have also been reported in multiple endocrine adenomatosis and in association with neurofibromatosis, tuberous sclerosis, and Carney complex. Diagnosis of Growth Hormone Excess The gold standard for making the diagnosis of GH excess is the failure to suppress serum GH levels to less than 5 ng /dL after 1.75 g / kg Blueprint in Pediatric Endocrinology 289

oral glucose challenge (maximum 75 g). This test measures the ability of IGF-1 to suppress GH secretion because the glucose load results in insulin secretion, leading to suppression of IGFBP-1, which results in an acute increase in free IGF-1 levels. The increased free IGF-1 suppresses GH secretion within 30–90 min. This test can be abnormal in diabetic patients. A single measurement of GH is inadequate because GH is secreted in a pulsatile manner. Therefore, the use of a random GH measurement can lead to both false-positive and false-negative results. Measurement of serum IGF-1 concentration is a sensitive screening test for GH excess. An elevated IGF-1 level in a patient with appropriate clinical suspicion is usually indicative of GH excess. Potential confusion may arise in the evaluation of normal adolescents, since significantly higher IGF-1 levels occur during puberty than in adulthood; the IGF-1 level must be age and gender-matched. Serum IGFBP-3 levels are sensitive markers of GH elevations and may be elevated despite normal IGF-1 levels. If laboratory findings suggest GH excess, the presence of a pituitary adenoma should be confirmed by MRI. In rare cases, a pituitary mass may not be identified. There may be an occult pituitary microadenoma or an ectopic tumor. Treatment of Growth Hormone oversecretion The goals of therapy are to remove or shrink the pituitary mass, to restore GH and secretory patterns to normal, to restore IGF-1 and IGFBP-3 levels to normal, to retain the normal pituitary secretion of other hormones, and to prevent recurrence of disease. For well- circumscribed pituitary adenomas, Transphenoidal surgery is the treatment of choice and may be curative. The tumor should be removed completely. The likelihood of surgical cure depends greatly on the surgeon's expertise as well as on the size and extension of the mass. Intraoperative GH measurements can improve the results of tumor resection. Transphenoidal surgery to resect the tumors is as safe in children as in adults. At times, a transcranial approach may be necessary. The primary goal of treatment is to normalize GH levels. GH levels of (<1 ng/ml within two hours after a glucose load) and serum IGF-1 levels (age-adjusted normal range) are the best tests to define a biochemical cure. If GH secretion is not normalized by surgery, the options include pituitary irradiation and medical therapy. Radiotherapy is recommended 290 Chapter 7: The Pituitary Gland

if GH hypersecretion is not normalized by surgery. Further growth of the tumor is prevented by irradiation in more than 99% of patients. The main disadvantage is the delayed efficacy in decreasing GH levels. GH is reduced by approximately 50% from the initial concentration by 2 years, by 75% by 5 years, and approaches 90% by 15 years. Hypopituitarism is a predictable outcome, occurring in 40–50% of patients 10 years after irradiation. Surgery fails to cure a significant number of patients, and therefore medical therapy has an important role in the management of patients with GH excess. Treatment is effective and well tolerated with long-acting somatostatin analogs and dopamine agonists as well as by novel GH antagonists. The somatostatin analogs are highly effective in the treatment of patients with GH excess. Octreotide suppresses GH to less than 2.5 ng/ml in 65% of patients with acromegaly and normalizes IGF-1 levels in 70%. The effects of octreotide are well sustained over time. Tumor shrinkage also occurs with octreotide but is generally modest. Consistent GH suppression can be obtained with a continuous SC pump infusion of octreotide in a pubertal boy with pituitary gigantism. Long-acting formulations, including long-acting octreotide and lanreotide, produce consistent GH and IGF-1 suppression in acromegalic patients with once monthly or biweekly intramuscular depot injections. The sustained- release preparations have not been formally tested in children. Octreotide injection in the pediatric population has been used as doses of 1–40 μg/kg/day. For patients having both GH and prolactin over secretion, dopamine agonists, such as Bromocriptine, which bind to pituitary dopamine type 2 (D2) receptors and suppress GH secretion, should be considered although their precise mechanism of action is unclear. Prolactin levels are often adequately suppressed; GH levels and IGF-1 levels are rarely normalized with this treatment modality. Fewer than 20% of patients achieve GH levels below 5 ng/ml, and fewer than 10% achieve normal IGF-1 levels. Tumor shrinkage occurs in a minority of patients. Bromocriptine is used as adjuvant medical treatment for GH excess. Its effectiveness may be additive to that of octreotide. Improved efficacy, defined by normal IGF-1 concentration and reduced tumor size, also occurs with other dopamine agonists (pergolide, cabergoline). The dose of Bromocriptine ranges from 10–60 mg/day Blueprint in Pediatric Endocrinology 291

orally divided into six hourly. However, only a minority of patients benefit from doses greater than 20 mg/day. It has been found safe when used in children for an extended period of time, but side effects may include nausea, vomiting, abdominal pain, arrhythmias, nasal stuffiness, orthostatic hypotension, sleep disturbances, and fatigue. The dose of cabergoline is 0.25–1 mg orally 1–2 times / week; however, a pediatric dose has not been established. GH-receptor antagonists specifically block the activity of GH at its effector sites. Pegvisomant is an analog of GH that competes with endogenous GH for binding to the GH receptor. It effectively suppresses GH and IGF-1 levels in patients with acromegaly due to pituitary tumors as well as ectopic GHRH hypersecretion. Normalization of IGF-1 levels occurs in up to 90% of patients treated daily with this drug for 3 months or longer. It has not been tested in children. The adult dose is 10–30 mg via subcutaneous injection once daily. Combined therapy with somatostatin analogs and weekly pegvisomant also is effective. Prolactinoma Prolactin-secreting pituitary adenomas are the most common tumors of the pituitary in adolescents. The most common presenting manifestations are headache, amenorrhea, and galactorrhea. The disorder affects more than twice as many girls as boys; most patients have undergone normal puberty before becoming symptomatic. Only a few have delayed puberty. In some kindred with type I multiple endocrine neoplasia (MEN), prolactinomas are the presenting feature during adolescence. Most prolactinomas in children are large (macroadenomas), cause the sella to enlarge, and in some cases cause visual field defects. Approximately one third of patients with macroadenomas develop hypopituitarism, particularly GH deficiency. Alternatively, prolactin- secreting adenomas may also stain for and secrete excess GH and/or TSH. Prolactinomas should not be confused with the hyperprolactinaemia and pituitary hyperplasia that may occur in patients with primary hypothyroidism, which is readily treated with thyroid hormone. Treatment for most children has been surgical resection by transfrontal or Transphenoidal approach. Prolactinoma can also be effectively managed medically in most patients by treatment with Bromocriptine or long-acting cabergoline. About 80% of adult patients 292 Chapter 7: The Pituitary Gland

respond with shrinkage of the tumor and marked decreases in serum prolactin levels. Corticotropinoma In pediatrics, corticotropinomas are the most common adenomas seen prepubertal although they occur at all ages. Cushing's disease refers specifically to an ACTH-producing pituitary adenoma that stimulates excess cortisol secretion. Adenomas causing Cushing's disease are significantly smaller than all other types of adenomas at presentation. The most sensitive indicator of excess glucocorticoid secretion in children is growth failure, which generally precedes other manifestations. Patients develop weight gain that tends to be centripetal rather than generalized. Pubertal arrest, fatigue, and depression are also common. Transphenoidal surgery is the treatment of choice for Cushing's disease in children. Further Reading 1. Pham PC, Pham PM, Pham PT. Vasopressin excess and hyponatremia. Am J Kidney Dis. 2006; 47(5):727-737. 2. Moritz ML, Ayus JC. Disorders of water metabolism in children: hyponatremia and hypernatremia. Pediatr Rev. 2002; 23(11):371-380. 3. Trachtman H. Cell volume regulation: a review of cerebral adaptive mechanisms and implications for clinical treatment of osmolal disturbances.Pediatr Nephrol. 1991; 5(6):743-750. 4. Maghnie M, Cosi G, Genovese E, et al. Central diabetes insipidus in children and young adults. N Engl J Med. 2000; 343(14):998-1007. 5. Russell TA, Ito M, Ito M, et al. A murine model of autosomal dominant neurohypophyseal diabetes insipidus reveals progressive loss of vasopressin- producing neurons. J Clin Invest. 2003; 112(11):1697-1706. 6. Rivkees SA, Dunbar N, Wilson TA. The management of central diabetes insipidus in infancy: desmopressin, low renal solute load formula, thiazide diuretics. J Pediatr Endocrinol Metab. 2007; 20(4):459-469. 7. Blanco EJ, Lane AH, Aijaz N, Blumberg D, Wilson TA. Use of subcutaneous DDAVP in infants with central diabetes insipidus. J Pediatr Endocrinol Metab. 2006; 19(7):919-925. 8. Jimenez R, Casado-Flores J, Nieto M, Garcia-Teresa MA. Cerebral salt wasting syndrome in children with acute central nervous system injury. Pediatr Neurol. 2006; 35(4):261-263. Blueprint in Pediatric Endocrinology 293

9. Palmer BF. Hyponatremia in patients with central nervous system disease: SIADH versus CSW. Trends Endocrinol Metab. 2003; 14(4):182-187. 10. Sterns RH, Silver SM. Cerebral salt wasting versus SIADH: what difference? J Am Soc Nephrol. 2008; 19(2): 194-196.

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Chapter 8

Diabetes in Children and Adolescents

. Introduction . Diagnosis of diabetes mellitus . Types 1 Diabetes Mellitus . Monogenic diabetes o MODY o Neonatal diabetes mellitus (NDM) . Transient NDM . Permanent NDM . Management of type 1 Diabetes Mellitus o Management of T1DM in toddlers o Fear of Hypoglycemia in Toddlers . Principles of insulin therapy o Conventional insulin regimens o Intensive insulin regimens . Continuos subcutaneous insulin infusion . Self-Monitoring of blood glucose . Continuous Glucose Monitoring System . Nutritional Therapy . Exercise . Psychosocial Support . Sick day management . Obesity and type 2 DM . T2DM management . Impaired glucose tolerance . Diabetes Ketoacidosis (DKA) o Precipitating Factors of DKA o Classification of DKA according to severity . Management of DKA o Fluid repletion in DKA

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o Insulin infusion o Electrolyte replacement in DM o Acid-base status o Management of the ketoacidosis recovery phase . Management of Diabetes during surgery require fasting . Hypoglycemia in a child with diabetes . Screening for Diabetes-Related Complications . Screening for other autoimmune diseases in T1DM . Treatment of diabetic complications

Introduction

The term ―diabetes‖ represents a chronic syndrome of impaired carbohydrate, protein and fat metabolism owing to insufficient secretion of insulin or target-tissue insulin resistance. Diabetes mellitus classified into type 1 diabetes (T1DM), type 2 diabetes (T2DM), Monogenetic forms of diabetes including maturity-onset diabetes of the young (MODY), mitochondrial diabetes, and neonatal diabetes mellitus (NDM). T1DM is caused by absolute insulin deficiency, which results from the autoimmune destruction of the pancreatic β cells in about 90% of cases which is labeled as Type 1A, while Type 1B is an idiopathic has clinical features of type 1A but without evidence of islet autoimmunity. Type 1A is due T-cell mediated pancreatic β cell destruction which occurs at variable rate. Monogenic diabetes which due to defects of β- cell functions includes; MODY with many various types have been so far described, which has young age of onset, autosomal dominant inheritance, the lack of association with obesity, and a variable phenotype. Neonatal diabetes which is usually happens in first six months of life. Mitochondrial diabetes which is due to maternal transmission of mutated deleted mitochondrial DNA can result in maternally inherited diabetes. This form of diabetes is characterized by progressive non-autoimmune β-cell failure and may progress to needing insulin treatment rapidly. A variety of other syndromes involving chromosomes (Down, Turner‘s and Klinefelter's syndromes), fat and muscle metabolism (Prader-Willi syndrome, Laurance-Moon-Biedl syndrome and myotonic dystrophy), autoimmune mechanisms (Stiff-man syndrome), neurological diseases (Freidrech's ataxia, Huntington's chorea) and porphria are associated with diabetes mellitus by affecting insulin secretion or sensitivity. Secondary causes of diabetes might include diseases of the exocrine pancreas that causes diabetes in children and adolescents as cystic fibrosis, chronic pancreatitis and iron overload as in hemosiderosis and hemochromatosis. Drug – or chemical induced diabetes for example (Glucocorticoid therapy used in the treatment of systemic illnesses is also commonly associated with hyperglycemia and diabetes, diazoxide, nicotinic acid, thiazides, pentamidine, chemotherapy e.g. L-Asperginase,

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(cyclosporine, tacrolimus which both might lead to permenant diabetes possibly due to islet cell destruction and antipsychotic medications including resperidol, olanzapine, ziprasidone). Genetic defects in insulin action (type A insulin resistance, Leprechaunism, Rabson-Mendenhall syndrome & lipoatrophic diabetes). Endocrinopathies causing secondary diabetes include (growth hormone excess, Cushing syndrome, glucagonoma, hyperthyroidism, pheochromocytoma and somatostatinoma). Table (8-1): Various Characterstics between Types of Diabetes in Children.

Characteristic Type 1 Type 2 MODY Post-pubertal 6 month to Obese children Age of onset except glucokinase adulthood & adults mutation autoimmunity Yes No No ketosis Common Uncommon Variable Obesity Lean Obese Lean or obese Acantosis Not present Present Not present Parents with diabetes 2-4% 80% 90% (positive history) Clinical Acute, rapid Slower Variable presentation onset Mostly less than 10 % except in % among young 90 % 1-2 % Japan up to60- 80% Genetics polygenic polygenic monogenic hyperglycemia Severe Variable Variable Diagnosis The classical symptoms of polyuria, polydipsia and weight loss over 2-4 weeks period are common. A thorough history and physical exam may reveal oral / perineal candidiasis or thrush. Such symptoms may be followed by nausea, abdominal pain with vomiting, lethargy, and Kussmaul respirations if diabetic ketoacidosis (DKA) develop. The presentation of T2DM in children and adolescents can be more subtle and sometimes even clinically silent. However, approximately a third of Blueprint in Pediatric Endocrinology 299

adolescents with T2DM have ketosis and a quarter has ketoacidosis at presentation. Diagnosis is based on a fasting plasma glucose of 7 mmole/L or greater (126 mg/dl or greater) on two separate occasions, a random plasma glucose of 11.1 mmole/l or greater (200 mg/dl or greater) with symptoms of polyuria or polydipsia, a plasma glucose level of 11.1 mmole/l or greater (200 mg/dl or greater) 2 hours after ingestion of glucose during an oral glucose tolerance test, or HbA1c 6.5% or greater. In the absence of unequivocal hyperglycemia, the test must be repeated to substantiate the diagnosis. Measurement of c-peptide and serological markers for autoimmunity (not routinely) e.g. islet cell autoantibodies (ICA), insulin autoantibody (IAA), gltamic acid decarboxylase (GAD), insulin, the insulinoma-associated 2 molecule (IA2) and zinc transporter 8 (ZnT-8) at diagnosis may help distinguish between type 1 and T2DM. Care must be taken to avoid delay in the diagnosis and initiation of treatment because of the risk of rapid metabolic deterioration with insulin deficiency. . Prediabetes includes impaired fasting glucose (IFG) & impaired glucose tolerance (IGT) . IFG is defined, when plasma glucose is between 5.6- 6.9 mmol/l ( 100-125 mg/dl) . IGT is defined, when plasma glucose 2 hours post 75 gram of glucose load is between 7.8 -11.1 mmol/l (140-199 mg/dl) Type 1 Diabetes Mellitus (T1DM) Is the result of an absolute deficiency of insulin secretion caused by an autoimmune process destroying β cells of the Pancreas The diagnosis can be confirmed by determining levels of hyperglycemia associated with the demonstration of anti-islet antibodies, particularly antiglutamic acid decarboxylase (anti-GAD). Finding a low insulin level is nonspecific, because the level may be functionally depressed by marked hyperglycemia, dehydration, or lipotoxicity. The patient may be genetically susceptible to other endocrine disorders, most commonly Hashimoto's thyroiditis, may occur before or after the onset of type 1 diabetes. 300 Chapter 8: Diabetes in Children and Adolescents

It may result from a viral destruction of β cells, as in congenital rubella, mumps, and cytomegalovirus and coxsackievirus infections. Although the etiological role of viral infections is controversial, coxsackie B3 and B4, cytomegalovirus, rubella, and mumps can infect human β cells. Congenital rubella infection is associated with diabetes in later life. It is estimated that 10–12% of patients infected with congenital rubella develop T1DM and up to 40% develop impaired glucose tolerance. The diabetes induced by congenital rubella resembles T1DM because it is associated with HLA-DR3 and HLA-DR4 and is mediated by immune responses against β-cell antigens. There has been no convincing correlation between childhood vaccinations and risk of T1DM. The pubertal peak in onset of type 1 DM occurs earlier in girls than boys. This sex difference might be mediated, in part, by estrogen or by genes regulated by estrogen, such as the interleukin-6 (IL6) gene, and suggests that pubertal changes may contribute to accelerated onset of type 1 DM in genetically susceptible females. Dietary factors have been implicated in the pathogenesis of T1DM, but the role of dietary factors in induction of islet autoimmunity remains controversial. Feeding cow's milk to animal models of T1DM has been associated with the development of diabetes in these animals. The likely mechanism is the molecular mimicry between a 17-amino-acid peptide of the bovine serum albumin and the islet antigen 69. Even though there appears to be a strong relationship between cow's milk consumption and diabetes in children, the role of cow's milk in human T1DM is controversial. N-nitroso compounds, derived from the conversion of nitrates from dietary vegetables and meat in the gut, have also been involved in the development of diabetes. The role of these compounds as a significant risk factor in the pathogenesis of diabetes remains controversial. An initial exposure of infants to cereals before 4 months of age has been suggested to increase the risk of islet autoimmunity. The risk of islet autoimmunity in both age groups is further increased in children who are positive for the HLA-DRB1*03/04, DQB8 genotype. Seasonal and long-term cyclic variations occur in the incidence of IDDM. Newly recognized cases appear with greater frequency in the autumn and winter months in the northern and southern hemispheres. Seasonal variations are most apparent in the adolescent years. Attempts Blueprint in Pediatric Endocrinology 301

to link a pattern of long-term cyclicity with the incidence of mumps or other viral infections have not been successful. . The American Diabetes Association (ADA) and the World Health Organization(WHO), have defined two sub-types of T1DM of: . Type 1A (autoimmune form) of T1DM, which accounts for approximately 90% of cases of T1DM in Caucasians and associated with circulating autoantibodies to the pancreatic islet antigens and is assumed to be due to autoimmune-mediated destruction of the β-cells. . Type 1B which is the idiopathic form of B-cell dysfunction or failure. Monogenic Diabetes (MODY & Neonatal Diabetes) MODY The term MODY dates back to 1964, when diabetes mellitus was considered to have two main forms: type 1 and type 2. By the 1990s, as the understanding of the pathophysiology of diabetes has improved, the concept and usage of "MODY" have become refined and narrower. It is now used as a synonym for dominantly inherited, monogenic defects of insulin secretion occurring at any age, and no longer includes any forms of type 2 diabetes. MODY is responsible for 2.4% of diabetes incidence in children aged less than 15 years. MODY is inherited in an autosomal dominant fashion, and most patients therefore have other members of the family with diabetes; penetrance differs between the types (from 40% to 90%). The recognized forms of MODY are all due to ineffective insulin production or release by islet pancreatic β-cells. Several different genetic abnormalities have been identified, each leading to a different type of disease. The subtypes of MODY are defined by specific descriptions of the known genetic defects. The genes involved control pancreatic beta cell development, function, and regulation, and the mutations in these genes cause impaired glucose sensing and insulin secretion with minimal or no defect in insulin action. Mutations in hepatocyte nuclear factor-1-alpha (HNF1A) and the glucokinase (GCK) gene are most commonly identified, occurring in 52 to 65 and 15 to 32 percent of MODY cases, respectively. Mutations in HNF4A account for approximately 10 percent of cases. Some members of a family have the genetic defect but do not develop 302 Chapter 8: Diabetes in Children and Adolescents

diabetes; the reason for this is unclear. Other patients may have the classic MODY phenotype but do not have an identifiable mutation in any of the MODY genes. Hepatocyte nuclear factor-4-alpha mutations (HNF4A) gene on chromosome 20 cause the condition formerly called MODY1. HNF4A is expressed both in the liver and in pancreatic beta cells. One of its functions is to regulate positively the activity of HNF1A, the affected gene in the previously labeled MODY3 syndrome. The secretory defect is progressive and patients typically present with hyperglycemia in adolescence or early childhood. Although the initial response to sulfonylureas is good, patients may require insulin as the secretory defect progresses. These patients are at risk for the microvascular and macrovascular complications of type 1 and type 2 diabetes mellitus. Defects in Glucokinase gene the expression, which phosphorylates glucose to glucose-6-phosphate and probably acts as a glucose sensor, result in a higher threshold for glucose stimulated insulin secretion. The resulting hyperglycemia is often stable, mild, and is not associated with the vascular complications that are so common in other types of diabetes mellitus. Patients with mutation in the glucokinase gene can often be controlled with diet alone. Mutation of hepatocyte nuclear factor-1-alpha (HNF1A) can lead to abnormal insulin secretion, also results in a low renal threshold for glucose. Patients with HNF1A diabetes have a similar clinical phenotype as patients with HNF4A diabetes. Patients with mutations in the HNF1a gene can be successfully treated with sulfonylurea monotherapy, and in some of patients previously treated with insulin successfully switched to sulfonylureas once an HNF1A mutation was identified. These patients are at risk for microvascular and macrovascular complications of type 1 and type 2 diabetes mellitus. In addition, patients with diabetes caused by a mutation in HNF1A appear to have an increased risk of cardiovascular mortality compared with unaffected family members. Mutations in the insulin promoter factor -1 (IPF1) gene can lead to what was called MODY4 by reduced binding of the protein to the insulin gene promoter and perhaps by altering fibroblast growth factor signaling in beta cells. Less severe mutations in IPF1 may predispose to late onset type 2 diabetes. Blueprint in Pediatric Endocrinology 303

Mutations in the hepatocyte nuclear factor-1-β (HNF1B) gene produce a syndrome that was formerly called MODY5. Affected patients can develop a variety of manifestations in addition to early onset diabetes. These include pancreatic atrophy (on CT scan), abnormal renal development (renal dysplasia that can be detected on ultrasonography in the fetus, single or multiple renal cysts, glomerulocystic disease, renal hypoplasia, slowly progressive renal insufficiency, hypomagnesemia, elevated serum aminotransferases, and genital abnormalities. In addition, some patients have a phenotype consistent with familial juvenile hyperuricemic nephropathy. Mutations of the neurogenic differentiation factor-1 (NEUROD1 or BETA2) can lead to what was called MODY6. NEUROD1 normally functions as a regulatory switch for endocrine pancreatic development. Other genes include, mutations in carboxyl ester lipase (CEL); insulin (INS); ATP-binding cassette, subfamily C, member 8 (ABCC8); potassium channel, inwardly rectifying, subfamily J, member 11 (KCNJ11); and paternal uniparental isodisomy of chromosome 6q24 (UPD6) genes have also been associated with the MODY phenotype. Mutations in INS, ABCC8, and KCNJ11 are more commonly associated with neonatal diabetes mellitus. It is important to distinguish MODY from type 1 and type 2 diabetes because the optimal treatment and risk for diabetes complications varies with the underlying genetic defect. As an example, patients with MODY due to HNF1A or HNF4A mutations are frequently misdiagnosed as having insulin requiring type 1 diabetes because they present at an early age and are not obese. However, many of these patients can be successfully managed with sulfonylureas monotherapy. In addition, distinguishing MODY from type 1 and type 2 diabetes allows earlier identification of at risk family members. Clinical Presentations There are two general types of presentations: Some forms of MODY produce significant hyperglycemia and the typical signs and symptoms of diabetes are increased thirst and urination (polydipsia and polyuria), while in contrast, many people with MODY have no signs or symptoms and are diagnosed either by accident, when a high 304 Chapter 8: Diabetes in Children and Adolescents

glucose is discovered during testing for other reasons, or screening of relatives of a person discovered to have diabetes. . MODY cases may make up as many as 5% of presumed type 1 and type 2 diabetes cases in a large clinic population.

The Following Features are Suggestive of MODY . Suspect when there is a strong family history of young onset diabetes involving 3 generations and onset prior to the age of 25 years. . Mild persistent hyperglycemia with a HbA1c at the upper limit of normal. . Type 2-like disease in a non-obese host. . Type 1-like disease in a host who has never had DKA or is still producing insulin beyond the honeymoon phase (prolonged honeymoon up to 3 years should suspect MODY). . Diabetes in children that are responsive to sulfonylurea should suspect MODY. . Mild (5.5-8.5 mmole/l) fasting hyperglycemia in young patients. MODY has been classified into many types depend on the gene mutations, but the commonest are; MODY1, hepatic nuclear factor HNF- 4 alpha mutation, patients are sensitive to sulfonylurea; MODY2, glukokinase mutation, patients do not need treatment in pediatric age and there is very little response to either oral hypoglycemic agents or insulin; MODY3, mutations in the HNF-1 alpha, the first treatment to be used in children is low dose sulfonylurea. MODY5, mutations in the HNF-1 beta, such patients usually require insulin treatment. . Monogenic diabetes (MODY or neonatal diabetes results from the inheritance of a mutation or mutations in single gene (dominant or recessive or a denovo mutation) . In over 80% of cases of monogenic diabetes, a molecular genetic diagnosis can be made by DNA testing, unlike T1DM and T2DM. . Monogenic diabetes confirmed only by genetic testing Blueprint in Pediatric Endocrinology 305

. Some forms of monogenic diabetes are sensitive to sulphonyluria drugs such as HNF-1α, HNF-4α and cases of neonatal diabetes due to Kir6.2 mutations. . Transient neonatal diabetes is usually diagnosed within the first week and resolves around 12 weeks. Management Unfortunately, chronic hyperglycemia of any cause can eventually cause blood vessel damage and the microvascular complications of diabetes. The principal treatment goal for people with MODY is keeping the blood glucose as close to normal as possible "good glycaemic control", while minimizing other vascular risk factors are the same for all known forms of diabetes. Tools available for management are also those available for all forms of diabetes: blood testing, changes in diet, physical exercise, oral hypoglycemic agents, and insulin injections. In many cases these goals can be achieved more easily with MODY than with ordinary types 1 and 2 diabetes. Some people with MODY may require insulin injections to achieve the same glycaemic control that another person may attain with careful eating or an oral medication. Neonatal Diabetes Mellitus (NDM) NDM is a monogenic form of diabetes that occurs in the first 6 months of life. It is a rare condition occurring in only one in 100,000 to 500,000 live births. The majority of infants are small for gestational age, which may be related to decreased insulin secretion in the fetus. They present with weight loss, volume depletion, hyperglycemia, and glucosuria with or without ketonuria and ketoacidosis. In about half of those with NDM, the condition is life-long and is called permanent neonatal diabetes mellitus (PNDM). In the rest of those with NDM, the condition is transient and disappears during infancy but can reappear later in life; this type of NDM is called transient neonatal diabetes mellitus (TNDM). Genetic mutations of the KIR6.2 subunit of the KATP channel can result in permanent neonatal diabetes mellitus, whereas mutations of the SUR1 subunit can result in either permanent or transient neonatal disease.

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Transient NDM Either paternal uniparental disomy of chromosome 6 or an unbalanced duplication of paternal chromosome 6 is present in the majority of cases of transient neonatal diabetes. Mutations of the imprinting gene ZAC/PLAG1, a transcriptional regulator of the type 1 receptor for pituitary adenylate cyclase-activating polypeptide, (an important regulator of insulin secretion), at chromosome 6q24 has been shown to be the major cause of neonatal transient DM. Activating mutations of the ABCC8 gene that encodes SUR1, the type 1 subunit of the sulfonylurea receptor, can cause either transient or permanent neonatal diabetes. Permanent NDM About one-half of patients with neonatal diabetes mellitus have a permanent form that is primarily due to gene mutations related to the ATP-sensitive potassium channel. Most patients with permanent neonatal diabetes mellitus have mutations that affect the ATP-sensitive potassium channel (KATP channel), which regulates the release of insulin from pancreatic beta cells. Activating mutations increase the number of open KATP channels at the plasma membrane, hyperpolarizing the beta cells, and preventing the release of insulin. . Inactivating mutations, described in children with persistent hyperinsulinemic hypoglycemia of infancy, reduce the number of open KATP channels, resulting in depolarization of the beta cells and persistent hypersecretion of insulin The KATP channel is composed of a small subunit Kir6.2 that surrounds a central pore and four regulatory SUR1 subunits. Activating gene mutations that affect these subunits can prevent insulin release, resulting in hyperglycemia. The most common cause of permanent neonatal diabetes is due to activating mutations in the KCNJ11 gene, which encodes Kir6.2. The diagnosis is made within the first two months of life. Infants are small for gestational age but exhibit postnatal catch-up growth with insulin therapy. Affected patients can also have neurologic abnormalities including severe developmental delay, epilepsy, muscle weakness, and dysmorphic features. These findings are also known as the DEND syndrome (developmental delay, epilepsy, neonatal diabetes). Subcutaneous insulin was routinely used in the past to treat patients with Blueprint in Pediatric Endocrinology 307

this disorder. However, oral sulfonylurea therapy appears to be more effective in controlling hyperglycemia. SUR1 activating mutations of the ABCC8 gene, which encodes SUR1 (the type 1 subunit of the sulfonylurea receptor), can cause both transient and permanent forms of neonatal diabetes. Oral sulfonylurea therapy normalized glycaemic control in patients with genetic mutations of SUR1. Neonatal diabetes mellitus has also been associated with mutations in other genes including RfX6, IPF-1, EIF2AK3, GCK, FOXP3, PTF1A, GLIS3, and the Ins2 genes. In some cases, these mutations result in pancreatic agenesis or hypoplasia, or absent β- cells. Children with permanent neonatal diabetes mellitus due to Wolcott- Rallison syndrome (diabetes mellitus, exocrine pancreatic insufficiency, and multiple epiphyseal dysplasia) have been shown to have hypoplastic pancreatic islets and a mutation in the EIF2AK3 gene that encodes translation initiation factor 2-α kinase 3. Finally, FOXP3 mutations cause a rare, X-linked disorder that presents in infancy with autoimmune endocrinopathy, enteropathy, and eczema. Other Beta-cell Gene Defects There are other rare genetic defects in beta-cell function that are not considered part of the MODY spectrum. One type results from a dominantly inherited missense mutation in the sulfonylurea 1 receptor subunit (SUR1) that causes hyperinsulinemia in childhood, but beta-cell dysfunction and diabetes in adulthood. Other examples include point mutations in mitochondrial DNA, genetic abnormalities that result in the inability to convert proinsulin to insulin, and the production of mutant insulin molecules. Genetic Defects in Mitochondrial DNA Maternally inherited diabetes and deafness (MIDD) is a rare mitochondrial disorder caused by a genetic mutation at position 3243 in transfer RNA. Although phenotypic expression is variable, subjects universally have both a defect in insulin secretion, which progresses to insulin dependence, and sensorineural hearing loss. The mean age of onset of diabetes and hearing loss is between the ages of 30 and 40. Other abnormalities seen include cardiac conduction defects, gestational diabetes, proteinuria, and neuropathy. 308 Chapter 8: Diabetes in Children and Adolescents

DIDMOAD "Wolfram syndrome" (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness) syndrome, originally described by Wolfram in 1938. This disorder is inherited as an autosomal recessive trait with incomplete penetrance. The gene responsible for the Wolfram syndrome, named WSF1, encodes an endoplasmic reticulum membrane-embedded protein called wolframin that is expressed in pancreatic beta cells and neurons. The estimated prevalence of Wolfram syndrome is 1 in 770,000 and it is believed to occur in 1 of 150 patients with type 1 diabetes .Affected patients usually develop insulin-requiring diabetes and optic atrophy in early childhood, and diabetes insipidus as teenagers or young adults. The last problem is due to loss of vasopressin-secreting neurons in the supraoptic nucleus and impaired processing of vasopressin. Anterior pituitary dysfunction has also been reported. Other manifestations of Wolfram syndrome include progressive sensorineural deafness, hydronephrosis (due in part to the high urine flow in diabetes insipidus), and neurologic dysfunction. Management of Type 1 Diabetes Mellitus The management of children and adolescents with diabetes requires a multidisciplinary team approach. In the first few months of outpatient diabetes care, patients are seen frequently by members of the diabetes team to assess the family's adaptation to the new diagnosis, reinforce skills and knowledge learned during the first few days, and expands on the skills and knowledge needed for intensive diabetes management. Management of Children with Diabetes . Balancing strict glycaemic control, which reduces the risk of long- term sequelae, and avoidance of severe hypoglycemia, which is more likely with stricter control. In children, targeted glycaemic goals define what is thought to be the best balance between these long- and short-term complications. . Setting realistic goals for each child and family. The patient's age and developmental status, and the level of family involvement are important factors in establishing a practical management plan that can be implemented by the patient and family. Blueprint in Pediatric Endocrinology 309

. Maintaining normal growth, development, and emotional maturation. Increasing independence and self-care as the child grows is an ongoing goal. . Training the patient and family to provide appropriate daily diabetes care in order to attain glucose control within the range of predetermined goals, and to recognize and treat hypoglycemia. Management of T1DM in Toddlers . Over the past decades there has been rapid increase in the incidence of diabetes in toddlers; some have tried to explain this via certain environmental factors such as: . Viral infections, e.g. Coxsackie and rotavirus infections. . The hygiene hypothesis, which suggests that the change in the gut flora leads to an over maturation in the immune system causing rare viral infections and an increased predisposition to autoimmune diseases, particularly affecting the pancreatic B-cells. . Nutritional factors mainly the lack of maternal breast feeding and depending on cow‘s milk in early life. . Lack of Vitamin D. . Exposure to toxic agents such as nitrosamines. Management . Parental education . Psychological evaluation and intervention . Hospitalization . Insulin regimens . Healthy diet, no more labeled as diabetic diet. Fear of Hypoglycemia in Toddlers Toddlers have good counter regulation, which decreases the chances of severe morbidity and mortality from hypoglycemic events and, in fact at this young age there is little negative effects on the intellectual development of toddlers from hypoglycemic events as young children can tolerate and function well at quite low blood glucose levels (1.5-3.5 310 Chapter 8: Diabetes in Children and Adolescents

mmole/l). The most dangerous effect of hypoglycemia is probably the anxiety of parents which may lead to hyperglycemia and extra food allowance. This dilemma can lead to prolonged hyperglycemia and ultimately lead to the development of diabetic complications in these children at a younger age. Age-based Management ADA Guidelines Children & Adolescents with Type 1 Diabetes . Infants (younger than 1 year of age) with diabetes have the highest risk of severe hypoglycemia. Hypoglycemia is difficult to detect because infants are unable to communicate their symptoms and clinical signs are nonspecific (e.g., poor feeding, lethargy, jitteriness, hypotonia). In addition, repeated episodes of hypoglycemia may have deleterious effects on brain development and learning, especially in children younger than five years of age. The frequent feeding schedule of infancy makes it challenging to develop a management plan that avoids episodes of hypoglycemia but provides sufficient glycaemic control. . Toddlers (1 to 3 years of age) are similar to those in infants. The parents must learn and be responsible for the daily care of the patient and also learn to recognize episodes of hypoglycemia. Hypoglycemia is a constant concern because of the erratic food intake and activity levels of toddlers. It also can be difficult to distinguish developmentally normal episodes of oppositional behavior and temper tantrums from altered behavior caused by hypoglycemia. The parents must learn to measure blood glucose before ignoring a temper tantrum. . Preschool and early school-aged children, parents still provide daily care for preschool and early school-aged children (3 to 6 years of age). As these children enter daycare or school, childcare providers and school nurses must be involved in their diabetes care. Continued support by the care team is important to facilitate this transition. Shared care with the child is appropriate at this age only under direct parental supervision . School-aged children (7 to 12 years of age) can learn to administer insulin injections on a routine basis, but still need significant assistance and supervision for management decisions that are not routine. Shared responsibility with appropriate adult supervision needs to be established for optimal care. The diagnosis of diabetes has a psychological impact on these children, which may be manifested by depression and anxiety. Blueprint in Pediatric Endocrinology 311

Children may also have difficulty with social interactions because of their perception that they are different from their peers. It is important for caregivers to recognize developing cognitive deficits and learning difficulties, and for appropriate care to be provided to children if these deficits develop. This is particularly important because of the higher risk of cognitive deficits in children who developed diabetes at a very young age, those with poor glycaemic control, frequent episodes of hypoglycemia and longer duration of the disease. . Diabetes education is an ongoing process with continuous need for review of previously learned material and introduction of new concepts and education needs to be tailored to each family taking into account their educational level and cultural practices. The educator must be sensitive to the age and developmental stage of the child or adolescent, and shift his or her educational efforts from the caregiver(s) to the adolescent when it is developmentally appropriate. . Continued parental involvement and supervision of the adolescent with diabetes is crucial to good metabolic control. Physical examination that includes measurement of blood pressure and heart rate, weight, height, body mass index (BMI), and examination of the thyroid gland, sites of blood glucose monitoring, and insulin injections should be completed at each visit. A more thorough physical examination including Tanner staging should be performed once per year or more frequently if indicated. The Hb A1C, the fraction of hemoglobin that has glucose attached to it, is a measure of the average level of blood glucose over the preceding 2 to 3 months. The Diabetes Control and Complications Trial (DCCT) demonstrated that the incidence of microvascular complications was reduced with improved blood glucose control (Hb A1C approximately 7%). The reduction in complications, however, was accompanied by an increased risk of severe hypoglycemia. Because young children are more vulnerable to hypoglycemia due to reduced catecholamine response to hypoglycemia, decreased ability to communicate symptoms of hypoglycemia, and increased risk for neuropsychological impairment from hypoglycemia. . HbA1c should be available in all centres caring for diabetes 312 Chapter 8: Diabetes in Children and Adolescents

. HbA1c is currently expressed as a percentage (%), however recently, the international federation of clinical chemistry and laboratory medicine (IFCC) has produced a reference values expressed in mmol/ mmol instead of %. . The conversion from mmol/mmol to % cab be by using the equation:HbA1c (%) = 0.0915 x IFC HbA1C (mmol/mmol) + 2.15

ADA has developed age-specific glycaemic target: . Those preschoolers HbA1c is between 7.5%–8.5%, 6–12years of age, <8% and those of 13–18 years of age of <7.5%. . Target fasting and preprandial blood glucose readings in the 100 - 180 mg/dL range for preschool aged children, 90-180 mg/dL for school- aged children and 90 to 130 mg/dL for teenagers are reasonable goals. . Bedtime or overnight levels of 110 to 200 mg/dL in preschoolers, 100 to 180 mg/dL in school-aged children, and 90 to 150 mg/dL in teenagers are also reasonable

IFCC HbA1c (mmol/mmol) DCCT (HbA1c (%) 42 6 48 6.5 53 7 58 7.5 64 8 69 8.5 75 9 80 9.5 86 10 97 11 108 12 119 13 129 14

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Insulin Therapy Exogenous administration of insulin is designed to replace the deficient hormone and to attain normoglycemia. There are many different insulin preparations and delivery systems are available. . The selected regimen is individualized for the child and family to fit their lifestyle and optimize compliance while providing glycaemic control that meets age-specific goals. Input from the patient, if age appropriate and the family (e.g., timing of meals and snacks, school/daycare, physical activity) is important to ensure optimal glycaemic control and minimize episodes of hypoglycemia Preparations Insulin types can be classified by their onset and duration of action. Rapid-acting (lispro, aspart, glulisine) and short-acting types (regular insulin) are typically administered as a premeal bolus (typically 5 to 15 minutes before the meal for the rapid-acting insulins, and 20 to 30 minutes before meals for the short-acting type) based on carbohydrate content of food and the blood glucose level. If necessary, rapid-acting insulin can be administered after the meal in younger children in whom intake is unpredictable. Rapid and short-acting insulins delivered by continuous subcutaneous infusion via an insulin pump provide basal insulin levels. Intermediate-acting NPH insulin is usually given two or three times a day. Long-acting insulin preparations (insulin glargine and insulin detemir) are given once for glargine or twice a day for detemir. They provide a basal insulin level that suppresses hepatic glucose production and maintains near-normal glucose levels in the fasting state. The starting dose of insulin replacement therapy depends on the age, weight, and pubertal status of the patient, as well as the presence or absence of DKA. For the prepubertal child the starting dose is usually 0.75 to 1 U/kg/day, while for the pubertal child 1 to 1.5 U/ kg /day. No single regimen is superior to another; thus individualization of the insulin regimen to the child or adolescent and family remains a major determinant. Important factors for consideration include blood glucose monitoring, frequency, number of daily injections the family can perform, the need for flexibility in meal planning, and the unique family schedule. Regimens range in intensity from twice-a-day injections to 314 Chapter 8: Diabetes in Children and Adolescents

intensive diabetes management with multiple injections per day of two types of insulin or use of an insulin pump (continuous subcutaneous insulin infusion. Principles of Insulin Therapy Conventional Insulin Regimens This traditional therapy includes administration of intermediate- acting insulin (NPH) at least twice a day (at breakfast and dinner), with rapid-acting or short-acting insulin two or three times a day. The rapid- or short-acting insulin would be given at breakfast and dinner, and sometimes at lunch or with the afternoon snack depending on blood glucose concentrations. This regimen is fixed and the patient and family must adjust their lifestyles so that meals and vigorous physical activity occur on a relatively fixed daily schedule. Two-thirds of the total daily dose is administered before breakfast (2/3 as NPH and 1/3 as rapid or short-acting insulin) and one-third before dinner and at bedtime (2/3 as NPH and 1/3 as rapid- or short-acting insulin). The dose of NPH can be split such that a portion is delivered before dinner and the remainder at bedtime. . Premixed insulins in our practice are seldomly to be used except in adolescents who are significantly non-compliant with their MDI regimen to reduce the number of the injections Intensive Insulin Regimens Patients on a basal-bolus regimen determine their insulin doses based on an insulin-to-carbohydrate ratio and a correction factor or sensitivity index (CF or SI). The insulin-to-carbohydrate ratio is the number of grams of carbohydrate covered by 1U of insulin (roughly 500 divided by total daily dose TDD) for each meal and snack. The CF/SI is the expected decrement in glucose following 1U of rapid-acting insulin (roughly 1500 divided by TDD). For patients on a combination of intermediate-acting insulin (NPH) and rapid or short-acting insulin, meals typically contain a certain amount of carbohydrates (e.g., 60g or 4 carbohydrate exchanges) and require consistency in timing to avoid hypoglycemia. Blueprint in Pediatric Endocrinology 315

Multiple Daily Injections (MDI) The next best regimen is intensive insulin treatment with long acting insulin basal insulin and short acting MDI before meals and as necessary with additional short-acting insulins at bedtime. While the choice of regimen is an individual matter of patient and physician preferences, we exclusively use glargine with short acting lispro, glulisine or aspart in our practice. We prefer glargine (Lantus) insulin to all other available long- acting insulin to provide our basal insulin requirements because it provides day-long basal insulin without significant peaks of action, such as confound NPH or insulin mixtures. Rapid acting insulin is relatively faster action makes it more suitable to cover carbohydrate boluses after the child has eaten, since appetites at young ages are often spurious. Continuos Subcutaneous Insulin Infusion (CSII) Since its‘ introduction in the late 1970s, CSII (insulin pump) has become an increasingly popular option for diabetes management. CSII is the most appropriate physiological regimen of insulin replacement, there are multiple models available and their operations continue to change with advancing technology. They contain multiple programs including basal and temporary basal rates, correction and carbohydrate boluses. They can be programmed according an individual‘s life style. Pre- programmed CSII automatically gives basal insulin (unit/hour) according to that individual‘s requirements and in addition temporary basal rates can be programmed for exercise or for inter-current infections. Again bolus doses can be automatically calculated by modern insulin pumps to help reduce calculation errors. Insulin pumps are as small as a pager and can hold 2-3 day supply of rapid acting insulin (Humalog, Apidra or Novorapid). All insulin pumps except OmniPod deliver insulin via a catheter to the subcutaneous tissues. The OmniPod system has created a system using disposable pumps which utilize a remote control. In CSII, the infusion site is best changed every 2-3 days to avoid skin infections and clogging up of the catheters. The advantages of CSII are that insulin is taken only when needed, and not in an anticipatory fashion as with long acting insulin, insulin boluses are taken to cover all carbohydrate food intakes whenever this is, no special diets as required, hypoglycemic episodes are minimal and the system is convenient and portable. This increased flexibility has the 316 Chapter 8: Diabetes in Children and Adolescents

greatest impact on the patients‘ quality of life. Another advantage is that basal rates can be lowered overnight when insulin requirements are at the lowest, and raised before waking time to prevent the glycaemic rise when growth hormone and cortisol levels go up inducing the ―dawn phenomenon‖. Such an over-night insulin excursion cannot be mimicked by long acting insulin. Whereas CSII has traditionally been reserved for adolescents' adults, it is gaining more widespread acceptance in children especially in infants and toddlers. Although parental supervision is maximum in this age group to monitor blood glucose levels and to give multiple insulin injections, it is usually difficult to achieve near-normal metabolic control in this population by MDI because of the extremely small insulin doses required due to marked insulin sensitivity, erratic dietary habits with unpredictable food intake, the varied activity level during the day and day to day, and frequent infections in this age group. As a result, infants face hypoglycemia and hyperglycemia episodes more often than older children. Therefore, we find that CSII is the ideal treatment option for this age group. In the past, there were concerns about safety and suitability of CSII in these young patients. The side effects of CSII is that since only short acting insulin (Humalog effects are mostly gone within 3-4 hours) are taken, any blockage (kinked or damaged catheter) or pump failure or forgetting to put the pump back on after showers or swimming etc can lead to rapid onset of hyperglycemia and /or ketoacidosis, with a rapid loss of control of diabetes and/or dehydration. Adolescents, especially girls who use pumps, complain that the treatment is uncomfortable, embarrassing, or unpleasant.

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Table (8-2): Advantages and Disadvantages of Continous Insulin Pump Infusion.

CSII Advantages CSII Disadvantages Less injections Slightly complicated for toddlers to understand Less psychological conflict Small chance of toddler manipulation Improves quality of life No residual insulin secretion

Easier for parents to manage then May cause rapid development repeated injections of ketoacidosis Easy to give meal boluses Increased need for self-control of both blood glucose and ketone bodies Less risk of night time hypoglycemia Misperception might lead to free diet and negligence to adherence of a diabetic diet Increased motivation of the diabetes Increased demands on the team managing team Is considered an educational tool for Expensive treatment patients, parents and the managing team Self-Monitoring of Blood Glucose Self-management of diabetes includes measuring blood glucose and blood / urine ketone levels, recording the results along with amount of carbohydrate intake and amount of insulin administered, and the ability to make insulin dosing decisions based on the interpretation of these records. Monitoring blood glucose four or more times daily is recommended in children with T1D. Additional monitoring may be necessary postprandially, overnight, or during periods of increased physical activity to help optimize control and prevent severe hypoglycemia. Preschool or early school-age children may require more frequent monitoring because of their inability to recognize symptoms or to communicate during episodes of hypoglycemia. In addition, children and adolescents using the insulin pump typically check their blood sugar six or more times per day. Ketones measurements should be done 318 Chapter 8: Diabetes in Children and Adolescents

whenever the blood glucose is greater than 250 to 300 mg/dl and/or if the patient is ill, especially with nausea, vomiting, or abdominal pain. Ketones can be measured either in the urine (acetoacetate and acetone) or blood (β-hydroxybutyric acid). Measurement of blood ketones is available on a home meter and is the preferred method in the current era stressing blood glucose monitoring.

Fig. (8-1): Showing Small Drop of Blood Needed for Home Monitoring. Continuous Glucose Monitoring System (CGMS) Subcutaneous glucose sensors that continuously measure interstitial fluid glucose levels are now available and approved for use in children. Short-term studies indicate clinical benefits of these devices as compared to conventional methods of blood glucose monitoring, when used by motivated and well-informed patients. These devices do not directly control insulin administration, but provide glucose readings to permit finer control of insulin administration by patients and their families. . The key to successful intensive diabetes management is frequent blood glucose monitoring, good record keeping, and communication of these results with the diabetes team at frequent intervals so that timely modifications can be made to the insulin regimen and /or meal plan. Blueprint in Pediatric Endocrinology 319

Fig. (8-2): Showing Mechanism of Testing Glucose through Interstitial Fluid. CGMS gives more detailed information on glycaemic control with respect to the time of meals, impact of insulin dosages, exercise and overnight glucose profile. It measures subcutaneous interstitial glucose every 5 minutes of the entire day continuously for 3-7 day periods and the information can be downloaded for analysis. CGMS has been used in patients with high variability of glucose values, or for assessment of glycaemic control at postprandial and overnight to optimize insulin therapy and metabolic control in patients with CSII. With the newest devices, it is possible to trace the direction and rate of change of glucose concentrations and therefore to make appropriate adjustments to the diabetes management. Some of the devices are also equipped with adjustable alarm for impending or actual hypoglycemia and hyperglycemia so that an immediate action can be taken. Furthermore, patients can adjust their insulin requirements throughout the day according to their lifestyle and set tight glucose targets without having hypoglycemia episodes. Multiple clinical trials have shown a significant reduction in HbA1c level in patients using CGMS. 320 Chapter 8: Diabetes in Children and Adolescents

Fig. (8-3): showing Pager-like Size of insulin Pump and Subcutaneous Sensor Integration. Nutritional Therapy in DM A dietician trained in pediatric nutrition and diabetes should help develop a meal plan that is individualized to the patient's daily schedule, food preferences, cultural influences, and physical activity. The meal plan is more likely to be successful if it is designed to fit into the family's already established schedule and preferences. The patient and family should also be instructed on carbohydrate counting so that either carbohydrate exchanges or insulin-to-carbohydrate ratios can be used. Like the child without diabetes, the total number of recommended calories follows the child's growth requirements along with consideration of the need for weight gain or loss. Growth velocity, weight gain, and BMI should be monitored at every visit to ensure that the meal plan is sufficient to meet the energy requirements of the patient. Unexpected weight loss or poor weight gain should prompt consideration of suboptimal metabolic control, as well as eating disorders, thyroid dysfunction, or gastrointestinal disease i.e. possibility of associated celiac disease. The ADA recommends that carbohydrates provide 45% to 65% of total calories, with protein and fat contributing 15% and 30%, Blueprint in Pediatric Endocrinology 321

respectively. The patient and family should be educated to avoid foods high in cholesterol, saturated fat, and concentrated sweets and select foods high in complex carbohydrate and dietary fiber. . All children and adolescents are recommended to have three meals per day. . If they receive intermediate-acting insulin preparations, they should also receive three snacks per day (morning, afternoon, and bedtime) to match anticipated peaks of insulin action. . If the child or adolescent is on a basal-bolus regimen, snacks are optional and require insulin coverage based on insulin-to-carbohydrate ratios. Exercise Exercise, or periods of sustained physical activity, can be beneficial to the patient by contributing to a sense of well-being, helping achieve the recommended BMI, improving glycaemic control (exercise enhances insulin sensitivity), improving the lipid panel (increasing HDL), and lowering blood pressure and improving cardiovascular fitness. All children and adolescents, especially those with diabetes, should be encouraged to participate in routine physical activity. The child or adolescent with diabetes needs to take precautions to avoid hypoglycemia during periods of increased physical activity. The patient and family need to check blood glucose before the initiation of activity, every hour during sustained activity, and at the completion of physical activity. Some children require additional carbohydrate before, during, and after activity; lower insulin doses on the days of increased physical activity; or both. It is suggested that the child take 15 g of carbohydrates, before exercise if the blood sugar is below target, and repeat it every 30 minutes of sustained activity. Rapid-acting carbohydrate should be readily available, and coaches and trainers should be aware of the diagnosis of diabetes and trained in the treatment of hypoglycemia especially how to use the "Glucagon injection" in cases of hypoglycemia associated with unconsciousness and or seizures, also very important for school teachers to be aware of all of these information to avoid unpleasant events happening to the child with diabetes. 322 Chapter 8: Diabetes in Children and Adolescents

Psychosocial Support in DM A thorough family assessment generally accompanies the diabetes diagnosis with appropriate referrals for additional services as needed. Family conflict, especially conflict over diabetes care, can be associated with deterioration in glycaemic control. Encouragement of ongoing family teamwork in the management of childhood diabetes promotes successful outcomes with respect to glycaemic control, reducing diabetes-specific conflict, and preventing acute complications and emergency assessments. Sick Day Management The goals for the management of children and adolescents during sick days are never omit insulin, prevent dehydration and hypoglycemia, monitor blood glucose frequently (every 2 to 4 hours), monitor for ketosis, provide supplemental rapid- or short-acting insulin doses (5% to 20% of TDD) depending on degree of hyperglycemia and ketosis, treat underlying illness, and have frequent contact with the diabetes team. The majority of DKA among children or adolescents with established diabetes is caused by insulin omission or errors in administration of insulin. Inadequate insulin therapy in the context of an intercurrent illness accounts for the remaining small percentage. Obesity and Type 2 DM

Fig. (8-4): Showing Abdominal Obesity in 10-year old Child with Increased Risk of type 2 diabetes. The recent rapid increase in the prevalence of T2DM in young patients is most likely to be due to changes in the environment: most importantly, the increasing prevalence of obesity. Most children are Blueprint in Pediatric Endocrinology 323

overweight (BMI 85% to 95% for age and gender) or obese (BMI > 95%) on BMI charts at diagnosis. . Total obesity is not as important as location of adipose tissue in causing insulin resistance. . Visceral fat is more metabolically active than subcutaneous fat in producing adipokines that cause insulin resistance. T2DM is a progressive disorder due to a deficit in both insulin secretion and insulin action leading to abnormal glucose metabolism and related metabolic derangements. Obesity, leading to insulin resistance, is the primary cause in children. The major etiological factor is obesity, although the inutero environment, birth-weight, early childhood nutrition, puberty, gender, ethnicity, and genetics also play a role in the development of insulin resistance and pre-disposition to T2DM in childhood. Children exposed to a diabetic intra-uterine environment had a 3.7 times increased risk of developing childhood T2DM as compared to siblings born before the mother became diabetic. The association of lower birth weight with later development of insulin resistance, impaired glucose tolerance, or T2DM suggests that inutero programming limits beta-cell capacity and induces insulin resistance in peripheral tissues. Rapid catch-up weight gain between birth and 2 years of age in babies born with a low birth weight has also been found to be associated with increased central adiposity and insulin resistance. Breastfeeding during infancy has been suggested to be protective against the development of T2DM in later childhood. Breastfeeding reduces the odds ratio for childhood obesity by approximately 20% as compared to formula feeding. An association between high protein intake in infancy and later obesity has also been suggested. Protein intake is 55% to 80% higher per kilogram of body weight in bottle-fed than breastfed infants. . The average age of diagnosis of T2DM is around puberty. . Puberty is associated with relative insulin resistance, reflected by a 2- to 3-fold increase in the peak insulin response to oral or intravenous glucose and 30% lower insulin-mediated glucose disposal. . When present with pre-existing insulin resistance, puberty may precipitate β -cell failure. 324 Chapter 8: Diabetes in Children and Adolescents

The majority of childhood-onset T2DM occurs in children from a high-risk ethnic background. Ethnic differences in insulin sensitivity are indicated by greater insulin responses to oral glucose in black children and adolescents compared with white children, adjusted for weight, age, and pubertal stage. An underlying genetic pre-disposition is indicating a 3.5 times greater risk of developing T2DM in siblings of affected individuals as compared with the general population, and from studies of monozygotic twins indicating an 80% to 100% concordance. T2DM is polygenic disease. With the increasing prevalence of childhood obesity during the last two decades, there is an increased occurrence of T2DM in youth. Prevalence of overweight children (defined as a body mass index greater than the 95th percentile for children and youth is increased .The epidemic of obesity follows the increased consumption of fast foods, increased consumption of soft drinks, increased sedentary behavior with more television watching, and decreased physical activity. Mirroring this epidemic of childhood obesity is the occurrence of T2DM in children and adolescents. T2DM occurs most commonly in those with a family history of T2DM; individuals from certain racial and ethnic minority groups including Native Americans, Hispanics, African Americans, and Asian and Pacific Islanders; those with obesity falling above the 85th percentile for BMI based on age and gender; and in association with markers of insulin resistance. Markers of insulin resistance include the occurrence of acanthosis nigricans and polycystic ovarian syndrome (PCOS). In addition, other well-known risk factors include hypertension and hyperlipidemia. . Because T2DM often goes without symptoms, individuals who are overweight, have a positive family history of T2DM, come from one of the high-risk racial and ethnic minority groups, and/or have markers of insulin resistance warrant screening for T2DM. T2DM Management Metformin is approved for the treatment of T2DM in children as in adults, but is the drug of choice for the treatment of insulin resistance in the absence of diabetes too. Some have suggested that it is the gastrointestinal side effects of the drug that accounts for much of its action. However the drug is effective in T2DM without weight loss, Blueprint in Pediatric Endocrinology 325

being found to reduce hepatic glucose output and increase insulin sensitivity in muscles amongst other actions. Metformin has various mechanisms of action in insulin resistance. Starting dose is 250 mg twice daily then increasing the doses to 500mg twice daily then an eventual dose of 850 mg TID in adolescents or 1000 mg twice daily. The maximum recommended daily dose of Metformin in youth is 2000mg/day. Often patients with T2DM present in ketoacidosis and require initial insulin therapy. The goal of management of the child with T2DM is initial stabilization often with insulin therapy, Metformin directed at managing the insulin resistance, and education. Once glucose levels are stabilized, insulin dosage may be lowered along with continued treatment with Metformin and approaches to lifestyle management. Lifestyle management involves a healthy diet, increasing exercise, and decreasing sedentary behaviors. Other medications used to treat T2DM; sulfonylureas, meglitinides, thiazolidinediones, and α-glucosidase inhibitors, none of which is currently approved for use in pediatric patients. There are ongoing studies to assess the efficacy and safety of these medications. The use of sulfonylurea in children with T2DM should be minimal. A typical initial sulfonylurea regimen consists of 2.5-5 mg of glipizide or glyburide taken 30 minutes before breakfast with another before dinner. Amaryl is a 24-hour sulfonylurea that can be given once daily at 2-8 mgs dosing and thus is the one that is used preferentially in our clinic. Sulfonylureas directly stimulate the KATP channel subunit containing the cytoplasmic binding sites for both sulfonylurea and ATP and result in the closure of the KATP channel and insulin secretion. However, as mentioned, hypoglycemia induced by a long-acting and concern of such agents might actually enhance progression to β cell failure. Thiazolidinediones (TZDs): There is no clinical experience with the use of thiazolidinediones (TZDs) in the prevention or treatment of T2DM in obese children. One reservation with their use has been with the instances of fatal hepatotoxicity seen with the prototype agent troglitazone, resulting in the FDA withdrawing the agent. This side effect has not been implicated with later agents of this class such as pioglitazone or rosiglitazone, albeit it should be monitored for. 326 Chapter 8: Diabetes in Children and Adolescents

Rosiglitazone can cause edema and have been implicated in cardiac complications among adults. Other medications indicated for treatment of T2DM, such as α- glucosidase inhibitor acarbose, lipase inhibitors, meglitinides are not often used in our pediatric practice as they are relatively ineffective and have significant side effects. Glucagon-like peptide-1 (GLP-1) receptor agonists and Dipeptidyl peptidase-4 (DPP-4) inhibitors is one of the intestinal pro-glucagon- derived peptides synthesized from pro-glucagon in the lower gut, mainly distal ileum and colon. It is an incretin hormone secreted in response to food intake rich in fat and carbohydrate. GLP-1 stimulates insulin secretion, inhibits glucagon secretion, improves β-cell sensitivity to glucose, increase postprandial insulin responses, regulates food intake by delaying gastric emptying and induces satiety. Subsequently, enhances the transition from the fasting to posprandial state by inhibiting endogenous hepatic glucose production and limits the postprandial hyperglycemia. In addition, it stimulates islet cell proliferation and differentiation while inhibiting apoptosis. It is a promising drug for the future in the management of T2DM. However, GLP-1 is rapidly metabolized by the dipeptidyl peptidase-4 (DPP-4) enzyme. To overcome this, GLP-1 receptor agonists and DPP-4 inhibitors have been developed. Studies with GLP-1 receptor agonist exenatide and liraglutide have shown significant decrease in blood glucose levels resulting in a reduction of Glycosylated HbA1c with minimum side effects (nausea, mild hypoglycemia). In addition there was a marked weight loss in subjects treated with GLP-1 receptor agonists. One relative problem with the agent is that it must be taken by injection before meals. DPP-4 inhibitors, sitagliptin (Januvia) and saxagliptin were introduced in 2006 and can be used alone or in combination with other oral anti-diabetics as mentioned above. Key Points on Type 2 DM . Increasing prevalence among children is related to increased prevalence of childhood obesity. . Etiology due to insulin resistance initially and later on insulin secretory defect. Blueprint in Pediatric Endocrinology 327

. Although not typical, can present in ketoacidosis (chronic high glucose impairs â-cell function and increases peripheral insulin resistance). . Consider screening by measuring fasting blood glucose levels among children who are overweight (body mass index more than 85th percentile for age and gender) and have two of the following risk factors:(1) Family history of type 2 DM in a first- or second-degree relative (2) Race/ethnicity: African American, Native American, Hispanic, or Asian or Pacific Islander (3) Signs associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovarian disease). . Begin at age 10 years or onset of puberty (whichever occurs first) and repeat every 2 years. . Based on adult data, HbA1c may be used as a screening tool . HbA1c =5.7%–6.4% indicates increased risk of future diabetes; 6.0%–6.5% is abnormal and indicates need for further testing (OGTT, fasting plasma glucose); > 6.5% is diagnostic of diabetes. . Treatment depends on primarily diet, exercise and oral pharmacologic agents. Insulin often necessary initially for those who are symptomatic at presentation and those presented with DKA. . Metformin has been used for patients with serum glucose levels <350 mg/dl without ketones. . Minimal data exists on the use of medications other than insulin and Metformin in children and adolescents. Until data on the efficacy and safety of these agents are demonstrated in studies in children, treatment with GLP-1 agonists, dipeptidyl-proteinase 4 inhibitors, pramlintide, andthiazolidinediones should not be used routinely in children Impaired Glucose Tolerance The term impaired glucose tolerance (IGT) refers to a metabolic stage that is intermediate between normal glucose homeostasis and diabetes. Many individuals with IGT (fasting glucose 100–125 mg/dl) are euglycemic in their daily lives and may have normal or nearly normal glycated hemoglobin levels. Individuals with IGT often manifest hyperglycemia only when challenged with the oral glucose load used in 328 Chapter 8: Diabetes in Children and Adolescents

the standardized oral glucose tolerance test.IGT is often associated with the insulin resistance syndrome (also known as syndrome X or the metabolic syndrome), which consists of insulin resistance, compensatory hyperinsulinism to maintain glucose homeostasis, obesity (especially abdominal or visceral obesity), dyslipidemia of the high-triglyceride or low or high-density lipoprotein type, or both, and hypertension. Diabetes Ketoacidosis (DKA) DKA is the leading cause of morbidity & mortality in children with type 1 diabetes mellitus ranging from 0.4 -1 % of patients with DKA. It can also occur in children with type 2 DM. In surveillance study in UK, 38 % occurred in patients at initial diagnosis of DM. In Middle East 60- 70% of newly diagnosed cases with type 1 DM presented with DKA. Children who are young (less than 5 years of age) or from low socioeconomic background are at increased risk for DKA at initial presentation because of symptoms unawareness. The annual incidence rate differs from community to other, range from 4.6 - 8 cases among 1000 cases of diabetes / year. It is the leading cause of acute death among patients with diabetes. Children or adolescents with established T1D are at higher risk for DKA if they are in poor metabolic control, have had a previous episode of DKA, are peripubertal /adolescent girls, have a behavioral disorders. Subcutaneous insulin is initiated in the patient who does not present in DKA. Precipitating Factors . Newly diagnosed type 1 or type 2 diabetes. . Infections (respiratory tract infection, urinary tract infections and sepsis). . Omission of insulin deliberately or due to poor education (missing insulin during inter-current illnesses). . Emotional stress (exam, interview, conflicts, menstruation …etc) . Unknown precipitating factor. . Poorly controlled diabetes culminating in DKA (those with high HgA1c level are at high risk).

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Prevention An educational program should include sick-day management instructions, including the use of short-acting insulin, blood glucose and urinary ketone monitoring, and the use of a liquid diet containing carbohydrates. Patients should not discontinue insulin therapy when they are ill, and they should contact their physician early in the course of illness. Clinical Features DKA clinical manifestations related to degree of hyperosmolality, volume depletion & metabolic acidosis. Hyperventilation & Kussmaul breathing represents respiratory compensation to metabolic acidosis. Patients may have fruity breath secondary to exhaled acetone. Neurological findings, ranging from drowsiness, lethargy & coma, are related to the severity of hyperosmolality. Severe neurological sign at presentation is poor prognostic factor, because these patients at increased risk for developing cerebral edema during therapy. Diagnostic Criteria . Hyperglycemia: blood glucose of more than 250 mg/dl (13.8 mmol/l). . Metabolic acidosis: venous pH of less than 7.30 and / or serum bicarbonate less than 15 meq/l. . Ketosis & ketonuria: presence of ketone bodies in blood or presence of keton in urine (more than +2). . Dehydration: usually 10 %, but it can be varying from mild dehydration, so careful assessment of degree of dehydration is very important step in the management.

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Classification of DKA According to Severity Table (8-3): Classification of DKA According to Severity. Mild Moderate Severe Plasma Glucose 250 (mg/dl) Arterial PH

Serum Bicarbonate Anion Gap Mental State Management of DKA Aim of Therapy . Correction of shock (if present). . Correction of dehydration. . Correction of hyperglycemia. . Correction of electrolyte deficit. . Correction of metabolic acidosis. . Treatment of the underlying cause. . Treatment of complications (if present). Treatment of DKA Requires Close Monitoring of The Following: . Clinical status including changes in vital signs. . Neurological status. . Fluid status (input / output chart). . Metabolic state (every 4-6 hours serum electrolytes, urea nitrogen & venous pH). . Changes in serum osmolality. . Hourly monitoring of blood glucose is needed with the initiation of fluid and insulin therapy to avoid hypoglycemia or rapid drop of glucose > 100 mg/hour.

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Important Calculations . Anion gap = [ Na+] - [ Cl- + HCO3-] . Corrected sodium (all values in mmole/l) = Sodium + 1.6 x (Glucose - 5.5) / 5.5 . Serum Osmolality (all values in mmole/l) = 2 x (Corrected sodium + potassium) + Glucose/18 + BUN/ 2.8 (if hospital units in mmole, no need to divide glucose on 18 or blood urea nitrogen on 2.8). . Serum sodium should be corrected for hyperglycemia Fluid Repletion in DKA Clinical estimates of extracellular fluid volume deficit are usually 10 % (but not always). Hypovolemic shock is a rare occurrence in DKA: Initial volume expansion should be with isotonic solution (Ringer's lactate or isotonic normal saline). Fluid repletion in severe DKA is usually begun with infusion of 10 ml / kg over 30- 60 minutes. If the circulating volume is still compromised, additional infusion of 10 ml/kg can be given over the next hour. Once the child is hemodynamically stable, subsequent fluid replacement should be given slowly over 36-48 hours to minimize risk of cerebral edema. This can be achieved by continued administration of isotonic saline till blood glucose less than 250 mg/dl then fluid will be changed to D5% in 0.45 saline. Urinary losses should not be added to the calculated total volume of fluids. Higher rates of fluid administration have been associated with development of cerebral edema Clinical Observations . Hourly pulse rate, respiratory rate, blood pressure, neurological observations. . Hourly blood glucose measurement while on an insulin infusion. . Accurate fluid balance (an indwelling catheter may be required). . Test all urine for ketone until negative. . Strict fluid balance is essential. Reassess fluid status every few hours. Continuing polyuria may worsen the dehydration if a positive fluid balance is not being achieved. The patient initially should be "Nil by Mouth" except for ice to suck. Rehydration should always be over 36 to 332 Chapter 8: Diabetes in Children and Adolescents

48 hours if the degree of ketoacidosis and dehydration is severe. If the corrected serum sodium value is in the hypernatremia range even slower rehydration may be considered. Initial rehydration fluid should be 0.9% Saline. KCl should be added at the commencement of rehydration unless the patient is known to have renal failure. Some centers use a combination of potassium chloride and potassium phosphate. Insulin Infusion Insulin to be started after resuscitation is completed; insulin therapy and KCl replacement should be started at the same time. In general the insulin infusion should commence at 0.075-0.1 units/kg/hour in children, not to give a priming bolus of insulin. The aim is to produce a fall in blood glucose of 4-5 mmole/l per hour. Over the first two hours however, rehydration alone will result in a fall in blood glucose and a larger fall can be accepted at this time without reduction in insulin infusion rate. When blood glucose falls below 14 mmol/l then the solution can be changed to 0.45% Saline and 5% Dextrose. The insulin infusion rate and/or the Dextrose infusion rate should then be adjusted to keep the blood glucose level between 8-12 mmole/l. Insulin is needed to clear the ketonaemia. When to switch to Subcutaneous Insulin? . Venous pH is > 7.30 & HCO3 is > 15 meq/l . Child is well hydrated. . No vomiting or abdominal pain. . Child is conscious, alert & willing to have oral intake. Electrolyte Replacement in DM Sodium Hyperglycemia results in osmotic water movement out of the cells, thereby lowering serum sodium concentration by dilution. This laboratory artifact is called "Pseudohyponatraemia". Reversing the hyperglycemia with insulin, will sequentially lower the plasma Osmolality, cause water to move from the extracellular fluid into the cells, and raise the serum sodium concentration. . Corrected serum sodium = sodium + 1.6 (glucose – 5.5) / 5.5 Blueprint in Pediatric Endocrinology 333

Failure of serum sodium to rise appropriately may be an early sign that the patient is at risk for cerebral edema. Sodium replacement is individualized on the basis of biochemical monitoring. If corrected sodium is greater than 150 mmole/l, hyperosmolar state exists and correction of the dehydration and electrolyte imbalance over 48 to 72 hours is advocated to minimize the risk of cerebral edema. Hyponatraemia during treatment is also of concern and usually reflects over-zealous volume correction and insufficient electrolyte replacement. Potassium Serum potassium at the time of presentation can be normal, increased, or decreased. Renal loss leads to marked degree of potassium depletion in DKA. These losses will tend to produce hypokalemia. Combination of insulin deficiency & acidosis impairs potassium entry into the cells & pulls potassium out of cells, tend to raise falsely serum potassium. Serum potassium should be carefully monitored during therapy. Electrocardiography monitoring is recommended in patients with either hypokalemia or hyperkalemia. Potassium replacement therapy should continue with intravenous insulin & fluid therapy till the child is shifted to subcutaneous insulin and has no longer metabolic acidosis. If there is no urine out or initial serum potassium is more than 5.5 meq/l, delay administration of potassium. Absence of bowel sounds (paralytic ileus) and loss of tendon jerks indicate extreme potassium deficiency. If initial serum potassium is normal (3.5 - 5.0 meq/L), add 30 meq to each liter of fluid. If initial serum potassium is low (less than3.5 meq/L), add 40 meq to each liter of fluid. Goal of replacement is to maintain plasma potassium level between 4 and 5 meq/l. Potassium is discontinued once patient resumes eating or drinking. . Regardless of the initial level, insulin therapy drives potassium into cells, resulting in fall in the serum potassium concentration!!! . In circumstances where continuous intravenous administration of insulin is not possible, 2 hourly SC or IM administration of a short-acting insulin (Regular insulin) or rapid-acting insulin analogue (insulin lispro, aspart or glulisine) may be used with insulin dose of 0.1 unit/kg every 1- 2 hours subcutanously. . When blood glucose is < 14 mmol/l (250 mg/dl), give glucose- containing fluids orally, and if needed, reduce SC insulin to 0.05 unit/kg 334 Chapter 8: Diabetes in Children and Adolescents

at 1-2 hour intervals to keep blood glucose ~ 11 mmol/l (200 mg/dl) until resolution of DK Phosphate Serum phosphate concentration may initially be normal or elevated due to movement of phosphate out of the cells. Phosphate depletion is rapidly unmasked following the institution of insulin therapy, frequently leading to hypophosphatemia. There have been concerns that low plasma phosphate levels could result in low level of erythrocyte 2, 3 diphosphoglycerate concentrations and its effect on tissue oxygenation. However, hypophosphatemia has not been shown to affect tissue oxygenation in adult patients with DKA and prospective studies of phosphate replacement in adults have failed to show clinical benefit. In addition to lack of efficacy in most patients, phosphate administration may induce hypocalcaemia. Despite the lack of evidence that phosphate therapy is beneficial, potassium phosphate has been used in some centers for concurrent potassium replacement in children with DKA. Careful monitoring of the serum calcium is required. Routine phosphate replacement is unnecessary in DKA. Acid-base Status Nitroprusside present in Ketostix reacts with acetoacetate & acetone but not β-hydroxybutyrate. In DKA, β-hydroxybutyrate makes up 75 % of the circulating ketones. Clinical testing with Nitroprusside may underestimate the severity of ketoacidosis & ketonuria. Blood testing for β-hydroxybutyrate (more reliable) is now available both in the clinical chemistry laboratory & at home. Insulin & fluid repletion leads to correction of acidosis seen in DKA. Insulin promotes metabolism of ketoacid anions, resulting in the generation of bicarbonate & stops ongoing production of new ketoacid. Improved tissue perfusion corrects any lactic acidosis. Avoid bicarbonate infusion unless severe acidosis (PH < 7, Hco3 < 5) or child in shock or in severe respiratory distress. Ketonuria may persist for > 36 hours due to slow removal of acetone . Bicarbonate therapy should not be used routinely in DKA . Controlled trials both in adults & children have been unable to demonstrate any clinical benefit from the routine administration of sodium bicarbonate Blueprint in Pediatric Endocrinology 335

In addition to lack of benefit, there are potential risks from bicarbonate therapy: . Can lead to rise in PCO2 resulting in paradoxical fall in cerebral PH as lipid-soluble CO2 rapidly crosses the blood-brain barrier. . May slow the rate of recovery of ketosis. . Can lead to over correction of metabolic alkalosis. . May be a risk factor for cerebral edema. . May result in Hypokalemia. . Can further increase degree of hypernatremia & hyperosmolality. . Bicarbonate, if needed should be given by a slow intravenous infusion over 30-60 minutes . Bicarbonate dose for total repair of base deficit as 1/3 (Base deficit x body weight in kg) however only 1/4 of this dose should be given at any one time and response noted before repeating or 1-2 mmole/ kg/ infusion, to be given very slowly unless hemodynamically compromised. Management of Ketoacidosis in Recovery Phase Use of Insulin Infusion to Cover Meals & Snacks It is useful to maintain the insulin infusion until the child has had at least one meal. For snacks the basal infusion rate is doubled at the start of the snack and continued for 30 minutes afterwards, before returning to the basal rate. For main meals the basal infusion rate should be doubled at the start of the meal and continued for 60 minutes after the meal, before returning to the basal rate. When to Stop Insulin Infusion? Subcutaneous insulin is given 30 minutes before the meal and insulin infusion continued throughout the meal for a total of 90 minutes after the subcutaneous insulin injection, then cease both insulin infusion and intravenous fluid. The half-life of intravenous insulin is only 4.5 minutes; therefore it is important that the subcutaneous insulin is given before stopping the infusion. Infections should be looked for repeatedly during DKA management and, if detected, should be treated promptly according to the nature of the infection. It should be noted that the patient in DKA 336 Chapter 8: Diabetes in Children and Adolescents

may not show fever initially but fever becomes apparent as the severity of the DKA diminishes and the patient's condition improves. Additional complications that may be present in DKA from the outset or may develop in the course of treatment include acute renal failure, cerebral edema, cerebral thrombosis and myocardial infarction depending on the age of the patient, duration of diabetes and quality of control of the diabetes. Other precipitating factors should also be treated accordingly. In severely sick patient where identification of a precipitating factor is difficult, broad spectrum antibiotic treatment could be justified. Treatment of Complications Cerebral Edema Cerebral edema is a complication of therapy that is reported to occur in 0.4 -1% of patients with DKA. Sub-clinical brain swelling, as detected by CT scan, has been much more common in most but not all studies. Pathophysiology It is generally believed that cerebral edema is related to management of DKA. Numerous factors have been implicated, but none has been proven. In addition, cerebral edema may be present before treatment has begun but more commonly occurs 4 -12 hours after the initiation of therapy. Therapy may exacerbate but not initiate the pathologic processes that lead to cerebral edema. Risk factors . Children with newly diagnosed diabetes. . Severity of acidosis at presentation. . The use of bicarbonate therapy for correction of the acidosis in DKA. . After adjusting for the severity of acidosis, a lower initial partial pressure of arterial carbon dioxide . The rate of decrease in plasma glucose concentration . The rate of fluid delivery . The initial glucose and sodium concentrations Blueprint in Pediatric Endocrinology 337

. Failure of the serum sodium to rise as predicted following insulin therapy and fluid repletion, indicating a greater fall in plasma osmolality. Treatment . Rate of fluid administration should be reduced. . Mannitol may be given intravenously at 0.25 -1.0 g / kg over 30 minutes. . This recommendation is based upon the suggested beneficial effect of mannitol in case reports. However, in one study of patients with cerebral edema, mannitol did not appear to have either a beneficial or detrimental effect. . The mannitol dose may be repeated in two hours, if there is no initial response. . Another potential hyperosmotic agent, 3 % saline at 5 -10 ml/kg over 30 minutes, has also been used but clinical experience is limited. . Intubation & mechanical ventilation may be required. . Aggressive hyperventilation (PCO2 below 22 mmHg) may decrease cerebral blood flow enough to cause cerebral ischemia& increase extent of brain injury in any form of cerebral edema. Other Complications . Venous thrombosis in children with DKA appears to be at increased risk for deep venous thrombosis, particularly in association with femoral central venous catheter placement. . Aspiration in children with DKA who present with an altered state of consciousness and vomiting are at increased risk for aspiration. . Cardiac arrhythmias may be seen with either hypokalemia or hyperkalemia. Management of Diabetes in Children & Adolescents during Surgery or Procedures The optimal method of maintaining metabolic control during surgery or fasting is by an insulin infusion, started when fasting commences. However for minor procedures under sedation or with short general 338 Chapter 8: Diabetes in Children and Adolescents

anesthetic where rapid post-operative recovery is expected, simpler regimens are possible. Emergency Surgery Unless absolutely necessary, emergency surgery should be delayed in any patient with ketoacidosis until diabetes control has improved and the diabetes stabilized. Diabetic ketoacidosis may by itself cause an acute abdomen which resolves with treatment of the ketoacidosis. Elective Surgery It should only be performed if diabetes is under good control. If control is uncertain or poor, admit 1-3 days beforehand for assessment and stabilization. If control remains poor, surgery should be cancelled and rebooked. Schedule operations early in the morning if possible. If not possible, schedule first on the afternoon list. This allows post-operative stabilization during the day. . Any child with diabetes who is fasting requires a continuous intravenous glucose infusion, adequate insulin replacement, hourly blood glucose monitoring and to maintain blood glucose levels of 5-10 mmole/L. Hypoglycemia in a child with diabetes Fear of hypoglycemia can be a common occurrence in the management of childhood diabetes. Families are trained to treat hypoglycemia with 15gram of rapid-acting carbohydrate, recheck blood glucose in 15 minutes, repeat treatment with 15gram if blood sugar remains below target, and follow with a protein-containing snack if a meal will not follow within 1 to 2 hours. This technique avoids the natural tendency to over treat low blood glucose levels. . Caregivers should also receive glucagon training (20 to 30 μg /kg; maximum 1mg) for severe hypoglycemia. Honeymoon Phase A few weeks after the diagnosis and initiation of insulin therapy, a period of decreasing exogenous insulin requirement occurs, commonly referred to as the "honeymoon" or remission phase of diabetes. During this period, the remaining functional beta cells secrete some endogenous insulin resulting in reduced exogenous requirement. Close monitoring of Blueprint in Pediatric Endocrinology 339

blood glucose is mandatory as hypoglycemic episodes are likely if the insulin dose is not appropriately adjusted. The duration of this phase is variable and may last several months to several years. Rising blood glucose levels, hemoglobin A1C, and increasing exogenous insulin need indicates the end of this phase. Screening for Diabetes-Related Complications Microalbuminuria (MA) is the first stage of diabetic nephropathy. Poor glycaemic control, smoking in adolescents, and a family history of hypertension are risk factors for the development of MA and nephropathy. Identification of persistent MA provides an opportunity for intervention and prevention of progressive renal disease through improvements in glycaemic control and/or therapy with angiotensin- converting enzyme (ACE) inhibitors. There are currently no pediatric data on the use of angiotensin receptor blockers (ARBs). . Urine collection should not be performed following vigorous exercise, during an acute infection, during a female patient's menstrual cycle, or following an episode of severe hypoglycemia. . Microalbuminuria (30-299 mg/g creatinine on of spot urine) Once angiotensin-converting enzyme (ACE) inhibitor is started, microalbumin excretion should be monitored every 3–6 months. Target BP is <130/ 80 or < 90th percentile for age, gender, and height. Initial drug treatment is ACE inhibitor. Hypertension is an important predictor of the progression of diabetic nephropathy to end-stage renal disease. Hypertension in children and adolescents may go unrecognized because providers are not familiar with the gender, age, and height-specific definitions. Blood pressure should be measured every 3 months with standardized technique, using the proper size cuff. Dyslipidemia and diabetes are established risk factors for cardiovascular disease, and recent research suggests that a significant proportion of adolescents with diabetes already have evidence of atherosclerosis. Low-density lipoprotein (LDL) cholesterol is most closely associated with cardiovascular disease, and therefore, the ADA has developed guidelines for LDL cholesterol. Screening may be delayed until puberty if family history is negative for cardiovascular disease. A lipid profile should be performed on prepubertal children with diabetes who are older than 2 years if there is a positive family history of 340 Chapter 8: Diabetes in Children and Adolescents

cardiovascular disease or if the family history is unknown. If the LDL cholesterol is less than 100mg/dl, screening can be repeated every 5 years. The mainstay of therapy for dyslipidemia is dietary management (saturated fat less than 7% of calories and less than 200mg/day of cholesterol). Children with levels between 130 and 159mg/dl should be started on medication if diet and lifestyle modification are unsuccessful after 6 months or if the child has additional risk factors for cardiovascular disease, such as obesity or hypertension. Pharmacotherapy is recommended if the LDL cholesterol is more than 160mg/dl. The LDL goal for children with diabetes is less than 100mg/dl. Diabetic retinopathy is a feared complication because it is the leading cause of vision loss. According to the ADA, the first ophthalmologic exam should be requested when the child is 10 years or older and has had diabetes for more than 3 to 5 years. Screening for Other Autoimmune Diseases in T1DM Children and adolescents with T1DM are at an increased risk for other autoimmune diseases and should be screened accordingly. Approximately 15% of patients with T1DM also have autoimmune thyroid disease. All children and adolescents should be screened for autoimmune thyroid disease at the time of diabetes diagnosis once metabolic control is established. TSH measurement is a useful initial screen, with and without measuring the presence of thyroid auto antibodies. Screening should be repeated yearly or if there is any clinical suspicion of thyroid disease (abnormal growth rate, symptoms of hypo- or hyperthyroidism, goiter on examination, erratic blood glucose control). Another commonly associated disorder is celiac disease. Nearly 6% of patients with T1DM have elevated levels of circulating autoantibodies to tissue transglutaminase. Celiac disease can cause diarrhea, weight loss or failure to gain weight, abdominal pain, fatigue, and unexplained hypoglycemia or erratic blood glucose secondary to malabsorption. Patients with T1DM should be screened with circulating IgA autoantibody to tissue transglutaminase. A quantitative serum IgA level should be drawn at the same time to rule out IgA deficiency as a cause for falsely low IgA tissue transglutaminase levels. Positive antibodies should be confirmed with a second measurement, and if positive, a referral should be made to a gastroenterologist for small bowel biopsy. If Blueprint in Pediatric Endocrinology 341

the diagnosis is confirmed, celiac disease is treated with a gluten-free diet with recommendations and support from a registered dietician with pediatric expertise in diabetes and celiac management. Treatment of Diabetic Complications Angiotensin converting enzyme (ACE) inhibitors are widely used for treatment of hypertension and microalbuminuria, and protection of the kidney against diabetes provoked damage. The combination of ACE inhibitors and angiotensin II receptor blocker (ARBs) has been proven beneficial for urinary albumin excretion. Poorly controlled diabetes induces rise in hepatic VLDL output and triglyceride levels. There is also a rise in total cholesterol, since 20% of VLDL is cholesterol. Whereas there may be a modest rise in LDL-cholesterol, a low level of the protective HDL-cholesterol is fairly constant with this atherogenic lipid profile. With severe (more than 500mg/dl) and/or chronic hypertriglyceridemia, pancreatitis may result. This is a serious problem with a mortality of some 20% with an acute attack. Diet reduced in animal fat and administration of fibrates (gemfibrozil) should be given to combat established hypertriglyceridemia. Fibrates lower triglycerides as mediated through the PPAR- factor, mainly in liver where it has an important role in fatty acid oxidation, gluconeogenesis, and amino acid metabolism. Statins inhibit 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, the rate-limiting enzyme in the mevalonate pathway through which cells synthesizes cholesterol. To compensate for decreased synthesis and to maintain cholesterol homeostasis, cells, particularly hepatocytes, increase the expression of LDL receptors, which increases the uptake of plasma LDL, the main carrier of extra-cellular cholesterol, resulting in lower plasma LDL concentrations. Key Points . Optimal management of a child with diabetes is defined by the implementation of a care plan that maintains glucose control as near to normal as safely possible, balancing the risks of long-term sequelae and hypoglycemia. . The management of childhood T1DM is dependent on the age of the patient, because the risk of hypoglycemia varies with age, age- 342 Chapter 8: Diabetes in Children and Adolescents

specific goals for glycaemic control be used, which are based upon the risk of hypoglycemia. . Although the choice of insulin regimen depends upon patient, family, and clinician preference, whenever possible we recommend that an intensive insulin regimen be selected for children with type 1 diabetes. . Intensive insulin therapy compared to conventional therapy improves glycaemic control and decreases long-term complications of diabetes. . Intensive insulin therapy combines the administration of a basal level of insulin together with premeal boluses of rapid-acting insulin. This regimen is delivered by two methods: (i) multiple daily injections (injections of a long-acting insulin analog once or twice daily and rapid- or short-acting insulin before meals and snacks), and (ii) insulin pump (continuous subcutaneous delivery of a rapid- or short-acting insulin with pre-meal boluses). . Both regimens require further family training, and increased family commitment and work. . Patients with diabetes and their families are at increased risk for psychological disorders such as depression and anxiety, which result in poor glycaemic control. . Addressing these psychosocial issues improves glycaemic control. . Frequency of follow-up visits is tailored to the needs of the child and family. . Follow-up visits monitor the child's glycaemic control and growth with appropriate readjustments to the management plan. Ongoing visits allow for continued family education and screening for complications of diabetes. . The prognosis of T1DM continues to improve with advances in home blood monitoring, in long acting insulin with modest peaks of action. . Rapid acting insulin suitable for meal boluses and insulin delivery systems exemplified by insulin pumps. Blueprint in Pediatric Endocrinology 343

. Rapid acting insulin does not cover snacks, so children and their parents should be advised that meal boluses don't cover snacks opposite to short-acting insulins where duration of action is longer than rapid acting insulin. . T2DM has emerged as the more serious form of childhood diabetes, while prevention of it through attention to the predisposing factors which are increasingly important to our public health. . The obesity epidemic continues unabated, with ever increasing numbers of the nation's obese children becoming irreversibly obese adults, replete with the insulin resistance in all of its' burgeoning complications, notably of progressive atherosclerotic disease, hypertension, increased frequencies of common cancers and T2DM. . Long term therapeutic trials that can show the long-term benefits of aggressive prevention and intervention, initially targeting highly prone ethnicities, are urgently needed. One interesting potential research development has been the creation of oral agents that lower the renal threshold for glucose. References and Further Reading 1. Jahromi MM, and Eisenbarth GS. Cellular and molecular pathogenesis of type 1A diabetes. Cell Mol Lif Sci. 2007; 64:865-872. 2. Emery LM, Babu S, Bugawam TL, et al. Newborn HLA-Dr, DQ genotype screening: age- and ethnicity-specific type 1 diabetes risk estimates. Pediatr Diabetes. 2005; 6:136-144. 3. Peng H, Hagopian W. Environmental factors in the development of type 1 diabetes. Rev Endocr Metab Disord. 2006; 7:149-162. 4. Expert Committee on the Diagnosis and Classification of Diabetes. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2007; S1:S42-S47. 5. Silverstein J, Klingensmith G, Copeland K, et al. Care of children and adolescents with type 1 diabetes: a statement of the American Diabetes Association. Diabetes Care. 2005; 28:186. 6. Weigand S, Raile K, Reinehr T, et al. Daily insulin requirement of childrena and adolescents with type 1 diabetes: effect of age, gender, body mass index and mode of therapy. Eur J Endocrinol. 2008; 158:543-549. 7. Chase HP, Dixon B, Pearson J, et al. Reduced hypoglycemic episodes and improved glycemic control in children with type 1 diabetes using insulin glargine and NPH. J Pediatr. 2003; 143:737-740. 344 Chapter 8: Diabetes in Children and Adolescents

Chapter 9

Hypoglycemia in Children and Adolescents

. Introduction . Neonatal hypoglycemia . Mechanism of normal insulin secretion . Persistent hypoglycemia in infants and children . Hyperinsulinism (PHHI) . Beckwith-Weidman syndrome . Endocrine hypoglycemia . Substrate Limited Ketotic Hypoglycemia . Branched-Chain Ketonuria (Maple Syrup Urine Disease) . Glycogen Storage Disease . Glucose-6-Phosphatase Deficiency . Disorders of Gluconeogenesis . Fructose-1, 6-Diphosphatase Deficiency . Defects in Fatty Acid Oxidation . Salicylate intoxication . Defects in Glucose Transporters o Glut-1 Deficiency o Glut-2 Deficiency . Systemic disorders associated with hypoglycemia . Diagnosis . Treatment

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Introduction Glucose supply and metabolism are of central importance for growth and normal brain development in the fetus and newborn. Hypoglycemia is defined as a serum glucose levels below 50 mg/dl (less than 2.5mmol/l) and concurrent with the patient's symptoms. Symptoms caused by hypoglycemia are associated with increased autonomic nervous system activity (adrenergic and cholinergic symptoms), and include anxiety, tremulousness, palpitation, sweating, nausea, and hunger. Severe hypoglycemia is commonly associated with symptoms of compromised central nervous system function because of brain glucose deprivation (neuroglycopenic symptoms). Neuroglycopenic symptoms include weakness, fatigue, confusion, seizures, focal neurologic deficit, and coma. Hypoglycemia occurs most frequently in patients being treated for diabetes, but also occurs with excessive alcohol intake, some medications, excess insulin secretion, and a variety of metabolic and hormonal abnormalities Neonatal Hypoglycemia Transient Causes The estimated incidence of symptomatic hypoglycemia in newborns is 1-3/1,000 live births. This incidence is increased several folds in certain high-risk neonatal groups. Premature and small for gestational age (SGA) infants are vulnerable to the development of hypoglycemia. The factors responsible for the high frequency of hypoglycemia in this group, are related to the inadequate stores of liver glycogen, muscle protein, and body fat needed to sustain the substrates required to meet energy needs. These infants are small by virtue of prematurity or impaired placental transfer of nutrients. Their enzyme systems for gluconeogenesis may not be fully developed. Transient hyperinsulinism responsive to diazoxide has also been reported as contributing to hypoglycemia in asphyxiated SGA, and premature newborn infants. This form of hyperinsulinism associated with perinatal asphyxia, small for gestational age, maternal toxemia and other perinatal stressors, is probably the most common cause of hyperinsulinemic hypoglycemia in neonates and may be quite severe. In most cases, the condition resolves

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quickly, but it may persist to six months of life or more. A genetic cause of this form of dysregulated insulin secretion has not been established. Infants born to diabetic mothers are the most common. Hypoglycemia is mostly related to hyperinsulinemia and partly related to diminished glucagon secretion. Infants born with erythroblastosis fetalis may also have hyperinsulinemia and share many physical features, such as large body size, with infants born to diabetic mothers. The cause of the hyperinsulinemia in infants with erythroblastosis is not clear. Mechanism of Normal Insulin Secretion Normally, glucose entry into the β cell is enabled by the non–insulin- responsive glucose transporter GLUT-2. On entry, glucose is phosphorylated to glucose-6-phosphate by the enzyme glucokinase, enabling glucose metabolism to generate ATP. The rise in the molar ratio of ATP relative to adenosine diphosphate (ADP) closes the ATP- sensitive potassium channel in the cell membrane (KATP channel). This channel is composed of two subunits, the KIR 6.2 channel, part of the family of inward-rectifier potassium channels, and a regulatory component in intimate association with KIR 6.2 known as the sulfonylurea receptor (SUR). Together, KIR 6.2 and SUR constitute the potassium-sensitive ATP channel KATP. Normally, the KATP is open, but with the rise in ATP and closure of the channel, potassium accumulates intracellularly, causing depolarization of the membrane, opening of voltage-gated calcium channels, influx of calcium into the cytoplasm, and secretion of insulin via exocytosis. Persistent Hypoglycemia in Infants and Children Hyperinsulinism Hyperinsulinism is the most common cause of persistent hypoglycemia in early infancy. Hyperinsulinemic infants may be macrosomic at birth, reflecting the anabolic effects of insulin in utero. There is no history or biochemical evidence of maternal diabetes. The onset is from birth to 18 months of age, but occasionally it is first evident in older children. Insulin concentrations are inappropriately elevated at the time of documented hypoglycemia; with non-hyperinsulinemic hypoglycemia, plasma insulin concentrations should be < 5 µU/ ml and no higher than 10 µU/ml. In affected infants, plasma insulin concentrations at the time of hypoglycemia are commonly > 5-10 µU/ml. Blueprint in Pediatric Endocrinology 349

Some authorities set more stringent criteria, arguing that any value of insulin >2 µU/ml with hypoglycemia is abnormal. The insulin (µU/ml): glucose (mg/dl) ratio is commonly > 0.4; plasma insulin-like growth factor binding protein-1 (IGFBP-1), ketones, and FFA levels are low with hyperinsulinemia. Macrosomic infants may present with hypoglycemia from the 1st days of life. Infants with lesser degrees of hyperinsulinemia may manifest hypoglycemia after the first few weeks to months, when the frequency of feedings has been decreased to permit the infant to sleep through the night and hyperinsulinism prevents the mobilization of endogenous glucose. Increasing appetite and demands for feeding, irritability spells, jitteriness, and frank seizures are the most common presenting features. Additional clues include the rapid development of fasting hypoglycemia within 4-8 hour of food deprivation compared with other causes of hypoglycemia; the need for high rates of exogenous glucose infusion to prevent hypoglycemia, often at rates > 10 - 15 mg per kg per minute; the absence of ketonaemia or acidosis; and elevated C-peptide or proinsulin levels at the time of hypoglycemia. The latter insulin-related products are absent in factitious hypoglycemia from exogenous administration of insulin as a form of child abuse (Munchausen by proxy syndrome). Hypoglycemia is invariably provoked by withholding feedings for several hours, permitting simultaneous measurement of glucose, insulin, ketones, and FFA in the same sample at the time of clinically manifested hypoglycemia. This is termed the ―critical sample.‖ The glycaemic response to glucagon at the time of hypoglycemia reveals a brisk increment in glucose concentration of at least 40 mg/dl, which implies that glucose mobilization has been restrained by insulin but that glycogenolytic mechanisms are intact. . Critical sample during the hypoglycemia attacks and 30 minutes after glucagon injection (glucagon 50 mcg /kg, maximum 1mg iv or IM) should include of the followings: glucose, free fatty acids, ketones, lactate, uric acid, ammonia, insulin, cortisol, growth hormone and thyroxin . Measure once only before or after glucagon administration . Rise in glucose of ≥ 40 mg/dl after glucagon given at the time of hypoglycemia strongly suggests a hyperinsulinemic state with adequate hepatic glycogen stores and intact glycogenolytic enzymes 350 Chapter 9: Hypoglycemia in Children and Adolescents

. If ammonia is elevated to 100 to 200 µM, consider activating mutation of glutamate dehydrogenase Criteria for Diagnosis of Hyperinsulinism Based on Critical Samples Drawn when Blood Glucose Less Than 50 mg/dl: . Hyperinsulinism (plasma insulin > 2 µU/ml). . Hypofattyacidemia (plasma free fatty acids < 1.5 mmole/l). . Hypoketonemia (plasma β-hydroxybutyrate < 2.0 mmole/l). . Inappropriate glycaemic response to glucagon, 1 mg intravenous (delta glucose change is more than 40 mg/dl).

The genes for both SUR and KIR 6.2 are located close together on the short arm of chromosome 11, the site of the insulin gene. Inactivating mutations in the gene for SUR or, less often, KIR 6.2 prevent the potassium channel from opening. It remains essentially variably closed with constant depolarization and, therefore, constant inward flux of calcium; hence, insulin secretion is continuous. The familial forms of PHHI are more common in certain populations, notably Arabic and Ashkenazi Jewish communities, where it may reach an incidence of about 1 / 2,500, compared with the sporadic rates in the general population of ≈1/50,000. The autosomal recessive forms of PHHI typically present in the immediate newborn period as macrosomic newborns with a weight more than 4.0 kg and severe recurrent or persistent hypoglycemia manifesting in the initial hours or days of life. Glucose infusions as high as 15- 20 mg/kg/minute and frequent feedings fail to maintain euglycemia. Diazoxide, which acts by opening KATP channels, fails to control hypoglycemia adequately. Somatostatin, which also opens KATP and inhibits calcium flux, may be partially effective in about 50% of patients. Calcium channel blocking agents have had inconsistent effects. When affected patients are unresponsive to these measures, pancreatectomy is strongly recommended to avoid the long-term neurologic sequelae of hypoglycemia. If surgery is undertaken, preoperative CT or MRI rarely reveals an isolated adenoma, which would then permit local resection. Intraoperative ultrasonography may identify a small impalpable Blueprint in Pediatric Endocrinology 351

adenoma, permitting local resection. Adenomas often present in late infancy or early childhood. Distinguishing between focal and diffuse cases of persistent hyperinsulinism has been attempted in several ways. Preoperatively, transhepatic portal vein catheterization and selective pancreatic venous sampling to measure insulin may localize a focal lesion from the step-up in insulin concentration at a specific site. Selective catheterization of arterial branches supplying the pancreas, followed by infusion of a secretagogue such as calcium and portal vein sampling for insulin concentration (arterial stimulation-venous sampling) may localize a lesion. Both approaches are highly invasive, restricted to specialized centers, and not uniformly successful in distinguishing the focal from the diffuse forms, hence, these techniques are not recommended. 18F-labeled L-dopa combined with PET scanning is a highly promising means to distinguish the focal from the diffuse lesions of hyperinsulinism unresponsive to medical management. The ―gold standard‖ remains intraoperative histological characterization. Diffuse hyperinsulinism is characterized by large β cells with abnormally large nuclei, whereas focal adenomatous lesions display small and normal β cell nuclei. Although SUR1 mutations are present in both types, the focal lesions arise by a random loss of a maternally imprinted growth-inhibitory gene on maternal chromosome 11p in association with paternal transmission of a mutated SUR1 or KIR 6.2 paternal chromosome 11p. Thus the focal form represents a double hit-loss of maternal repressor and transmission of a paternal mutation. Local excision of focal adenomatous islet cell hyperplasia results in a cure with little or no recurrence. For the diffuse form, near-total resection of 90-95% of the pancreas is recommended. The near-total pancreatectomy required for the diffuse hyperplastic lesions is, however, often associated with persistent hypoglycemia with the later development of hyperglycemia or frank, insulin-requiring diabetes mellitus. Further resection of the remaining pancreas may occasionally be necessary if hypoglycemia recurs and cannot be controlled by medical measures, such as the use of somatostatin or diazoxide. A second form of familial PHHI suggests autosomal dominant inheritance. The clinical features tend to be less severe, and onset of hypoglycemia is most likely, but not exclusively, to occur beyond the immediate newborn period and 352 Chapter 9: Hypoglycemia in Children and Adolescents

usually beyond the period of weaning at an average age at onset of one year of age. At birth, macrosomia is rarely observed, and response to diazoxide is almost uniform. The initial presentation may be delayed and rarely occur as late as 30 years, unless provoked by fasting. The activating mutation in glucokinase is transmitted in an autosomal dominant manner. If a family history is present, genetic counseling for a 50% recurrence rate can be given for future offspring. A third form of persistent PHHI is associated with mild and asymptomatic hyperammonemia, usually as a sporadic occurrence, although dominant inheritance occurs. Presentation is more like the autosomal dominant form than the autosomal recessive form. The association of hyperinsulinism and hyperammonemia is caused by an inherited or de novo gain-of-function mutation in the enzyme glutamate dehydrogenase. The resulting increase in glutamate oxidation in the pancreatic β cell raises the ATP concentration and, hence, the ratio of ATP: ADP, which closes KATP, leading to membrane depolarization, calcium influx, and insulin secretion. In the liver, the excessive oxidation of glutamate to β- ketoglutarate may generate ammonia and divert glutamate from being processed to N-acetylglutamate, an essential cofactor for removal of ammonia through the urea cycle via activation of the enzyme carbamoyl phosphate synthetase. The hyperammonemia is mild, and produces no CNS symptoms or consequences, as seen in other hyperammonemic states. Leucine, a potent amino acid for stimulating insulin secretion and implicated in Leucine-sensitive hypoglycemia, acts by allosterically stimulating glutamate dehydrogenase. Thus, Leucine-sensitive hypoglycemia may be a form of the hyperinsulinemia-hyperammonemia syndrome or a potentiating of mild disorders of the KATP channel; it need not always be associated with a modest increase in serum ammonia. Beckwith-Weidman Syndrome Hyperinsulinemia is seen in about 50% of patients. It is characterized by omphalocele, gigantism, macroglossia, microcephaly, and visceromegaly. Distinctive lateral earlobe fissures and facial nevus flammus are present; hemihypertrophy occurs in many of these infants. Diffuse islet cell hyperplasia occurs in infants with hypoglycemia. The diagnostic and therapeutic approaches are the same as those discussed previously, although microcephaly and retarded brain development may occur independently of hypoglycemia. Patients with the Beckwith- Blueprint in Pediatric Endocrinology 353

Weidman syndrome may acquire tumors, including Wilms tumor, hepatoblastoma, adrenal carcinoma, gonadoblastoma, and rhabdomyosarcoma. This overgrowth syndrome is caused by mutations in the chromosome 11p15.5 region close to the genes for insulin, SUR, KIR 6.2, and IGF-2. Duplications in this region and genetic imprinting from a defective or absent copy of the maternally derived gene are involved in the variable features and patterns of transmission. Hypoglycemia may resolve in weeks to months of medical therapy. Pancreatic resection may also be needed. After the first year of life, hyperinsulinemic states are uncommon until islet cell adenomas reappear as a cause after the patient is several years of age. Hyperinsulinemia due to islet cell adenoma should be considered in any child 5 years or older presenting with hypoglycemia. Islet cell adenomas do not ―light up‖ during scanning with L-dopa labeled with fluorine-18. An islet cell adenoma in a child should arouse suspicion of the possibility of multiple endocrine neoplasia type 1 (Wermer syndrome), which involves mutations in the menin gene and may be associated with hyperparathyroidism and with pituitary tumors. Fasting for up to 24-36 hour usually provokes hypoglycemia; coexisting hyperinsulinemia confirms the diagnosis, provided that factitious administration of insulin by the parents, a form of Munchausen syndrome by proxy, is excluded. Occasionally, provocative tests may be required. Exogenously administered insulin can be distinguished from endogenous insulin by simultaneous measurement of C-peptide concentration. If C- peptide levels are elevated, endogenous insulin secretion is responsible for the hypoglycemia; if C-peptide levels are low but insulin values are high, exogenous insulin has been administered, perhaps as a form of child abuse. Islet cell adenomas at this age are treated by surgical excision. Antibodies to insulin or the insulin receptors are also rarely associated with hypoglycemia. Some tumors produce insulin-like growth factors, thereby provoking hypoglycemia by interacting with the insulin receptor. The clinician must also consider the possibility of deliberate or accidental ingestion of drugs such as a sulfonylurea or related compound that stimulates insulin secretion. In such cases, insulin and C-peptide concentrations in blood will be elevated. Inadvertent substitution of an insulin secretagogue by a dispensing error should be considered in those taking medications that suddenly develop documented hypoglycemia. 354 Chapter 9: Hypoglycemia in Children and Adolescents

Hypoglycemia with so-called nesidioblastosis has also rarely been reported after bariatric surgery for obesity. The mechanism for this form of hyperinsulinemic hypoglycemia remains to be defined. Infants and children with Nissen fundoplication, a relatively common procedure used to ameliorate gastroesophageal reflux, frequently have an associated ―dumping‖ syndrome with hypoglycemia. Characteristic features include significant hyperglycemia of up to 500 mg/dl 30 min postprandially and severe hypoglycemia (average 32 mg/dl in 1 series) 1.5- 3.0 hour later. The early hyperglycemia phase is associated with brisk and excessive insulin release that causes the rebound hypoglycemia. Endocrine Deficiency Hypoglycemia associated with endocrine deficiency is usually caused by adrenal insufficiency with / without associated growth hormone deficiency. In patients with panhypopituitarism, isolated adrenocorticotropic hormone or growth hormone deficiency, or combined ACTH deficiency plus growth hormone deficiency, the incidence of hypoglycemia is as high as 20%. In the newborn period, hypoglycemia may be the presenting feature of hypopituitarism; in males, a Microphallus may provide a clue to a coexistent deficiency of gonadotropin. Newborns with hypopituitarism often have a form of ―hepatitis‖ associated with cholestatic jaundice and hypoglycemia. The combination of hypoglycemia and cholestatic jaundice requires exclusion of hypopituitarism as a cause, since the jaundice resolves with replacement treatment of growth hormone, cortisol, and thyroid as required. This constellation is often associated with the syndrome of septo-optic dysplasia. When adrenal disease is severe, as in congenital adrenal hyperplasia caused by cortisol synthetic enzyme defects, adrenal hemorrhage, or congenital absence of the adrenal glands, disturbances in serum electrolytes with hyponatraemia and hyperkalemia or ambiguous genitals may provide diagnostic clues. In older children, failure of growth should suggest growth hormone deficiency. Hyperpigmentation may provide the clue to Addison disease with increased ACTH levels or adrenal unresponsiveness to ACTH owing to a defect in the adrenal receptor for ACTH. The frequent association of Addison disease in childhood with hypoparathyroidism (hypocalcaemia), chronic mucocutaneous candidiasis, and other endocrinopathies should be Blueprint in Pediatric Endocrinology 355

considered. Adrenoleukodystrophy should also be considered in the differential diagnosis of primary Addison disease in older male children. Hypoglycemia in cortisol and growth hormone deficiency may be caused by decreased gluconeogenic enzymes with cortisol deficiency, increased glucose utilization due to a lack of the antagonistic effects of growth hormone on insulin action, or failure to supply endogenous gluconeogenic substrate in the form of alanine and lactate with compensatory breakdown of fat and generation of ketones. Deficiency of these hormones results in reduced gluconeogenic substrate, which resembles the syndrome of ketotic hypoglycemia. Investigation of a child with hypoglycemia, therefore, requires exclusion of ACTH-cortisol or growth hormone deficiency and, if diagnosed, its appropriate replacement with cortisol or growth hormone. Epinephrine deficiency could theoretically be responsible for hypoglycemia. Urinary excretion of epinephrine has been diminished in some patients with spontaneous or insulin-induced hypoglycemia in whom absence of pallor and tachycardia was also noted, suggesting that failure of catecholamine release, due to a defect anywhere along the hypothalamic-autonomic-adrenomedullary axis, might be responsible for the hypoglycemia. This possibility has been challenged, owing to the rarity of hypoglycemia in patients with bilateral adrenalectomy, provided that they receive adequate glucocorticoid replacement, and because diminished epinephrine excretion is found in normal patients with repeated insulin-induced hypoglycemia. Many of the patients described as having hypoglycemia with failure of epinephrine excretion fit the criteria for ketotic hypoglycemia. Also, repetitive hypoglycemia leads to diminished cortisol plus epinephrine responses, as seen most commonly in insulin-treated diabetes mellitus and the syndrome of hypoglycemia unawareness.Glucagon deficiency in infants or children may theoretically be associated with hypoglycemia but has never been fully documented. Substrate Limited Ketotic Hypoglycemia Ketotic hypoglycemia is the most common form of childhood hypoglycemia. This condition usually presents between the ages of 18 months and 5 year and commonly remits spontaneously by the age of 8-9 year. Hypoglycemic episodes typically occur during periods of intercurrent illness when food intake is limited. 356 Chapter 9: Hypoglycemia in Children and Adolescents

. The classic history is of a child who eats poorly or completely avoids the evening meal, is difficult to arouse from sleep the following morning and hence eats poorly again, and may have a seizure or be comatose by mid-morning. . Another common presentation occurs when parents sleep late and the affected child is unable to eat breakfast, thus prolonging the overnight fast. At the time of documented hypoglycemia, there is associated ketonuria and ketonemia; plasma insulin concentrations are appropriately low, thus excluding hyperinsulinemia. A ketogenic provocative diet, formerly used as a diagnostic test, is no longer used to establish the diagnosis because fasting alone provokes a hypoglycemic episode with ketonemia and ketonuria within 12 - 18 hour in susceptible individuals. Normal children of similar age can withstand fasting without hypoglycemia developing during the same period, although even normal children may acquire these features by 36 hour of fasting. Children with ketotic hypoglycemia have plasma alanine concentrations that are markedly reduced in the basal state after an overnight fast and decline even further with prolonged fasting. Alanine, produced in muscle, is a major gluconeogenic precursor. Alanine is the only amino acid that is significantly lower in these children, and infusions of alanine (250 mg/kg) produce a rapid rise in plasma glucose without causing significant changes in blood lactate or pyruvate levels, indicating that the entire gluconeogenic pathway from the level of pyruvate is intact, but that there is a deficiency of substrate. The etiology of ketotic hypoglycemia may be a defect in any of the complex steps involved in protein catabolism, oxidative deamination of amino acids, transamination, alanine synthesis, or alanine efflux from muscle. Children with ketotic hypoglycemia may represent the low end of the spectrum of children's capacity to tolerate fasting. Similar relative intolerance to fasting is present in normal children, who cannot maintain blood glucose after 30-36 hour of fasting, compared with the adult's capacity for prolonged fasting. Although the defect may be present at birth, it may not be evident until the child is stressed by more prolonged periods of calorie restriction. Blueprint in Pediatric Endocrinology 357

. Spontaneous remission observed in children at age 8-9 year might be explained by the increase in muscle bulk with its resultant increase in supply of endogenous substrate and the relative decrease in glucose requirement per unit of body mass with increasing age. . During intercurrent illnesses, parents should test the child's urine for the presence of ketones, the appearance of which precedes hypoglycemia by several hours. In the presence of ketonuria, liquids of high carbohydrate content should be offered to the child. If these cannot be tolerated, the child should be cared for in a hospital with intravenous glucose administration. Branched-Chain Ketonuria (Maple Syrup Urine Disease) The hypoglycemic episodes were once attributed to high levels of Leucine, but evidence indicates that interference with the production of alanine and its availability as a gluconeogenic substrate during calorie deprivation is responsible for hypoglycemia. Glycogen Storage Disease (GSD) Glucose-6-Phosphatase Deficiency (Type 1 GSD) Affected children usually display a remarkable tolerance to their chronic hypoglycemia; blood glucose values in the range of 20-50 mg/dl are not associated with the classic symptoms of hypoglycemia, possibly reflecting the adaptation of the CNS to ketone bodies as an alternative fuel. Low hepatic phosphorylase activity may result from a defect in any of the steps of activation; a variety of defects have been described. Hepatomegaly, excessive deposition of glycogen in liver, growth retardation, and occasional symptomatic hypoglycemia occur. A diet high in protein and reduced in carbohydrate usually prevents hypoglycemia. Disorders of Gluconeogenesis Fructose-1, 6-Diphosphatase Deficiency A deficiency of this enzyme results in a block of gluconeogenesis from all possible precursors below the level of fructose-1, 6-diphosphate. Infusion of these gluconeogenic precursors results in lactic acidosis without a rise in glucose; acute hypoglycemia may be provoked by inhibition of glycogenolysis. Glycogenolysis remains intact, and 358 Chapter 9: Hypoglycemia in Children and Adolescents

glucagon elicits a normal glycaemic response in the fed, but not in the fasted, state. Accordingly, affected individuals have hypoglycemia only during caloric deprivation, as in fasting, or during intercurrent illness. As long as glycogen stores remain normal, hypoglycemia does not develop. In affected families, there may be a history of siblings with known Hepatomegaly who died in infancy with unexplained metabolic acidosis. Defects in Fatty Acid Oxidation The important role of fatty acid oxidation in maintaining gluconeogenesis is underscored by examples of congenital or drug- induced defects in fatty acid metabolism that may be associated with fasting hypoglycemia. Various congenital enzymatic deficiencies causing defective carnitine or fatty acid metabolism occur. A severe and relatively common form of fasting hypoglycemia with hepatomegaly, cardiomyopathy, and hypotonia occurs with long- and medium-chain fatty acid coenzyme-A dehydrogenase deficiency (LCAD and MCAD). Plasma carnitine levels are low, ketones are not present in urine, but dicarboxylic aciduria is present. Clinically, patients with acyl CoA dehydrogenase deficiency present with a Reye-like syndrome, recurrent episodes of severe fasting hypoglycemic coma, and cardiorespiratory arrest (sudden infant death syndrome-like events). Severe hypoglycemia and metabolic acidosis without ketosis also occur in patients with multiple acyl CoA dehydrogenase disorders. Hypotonia, seizures, and acrid odor are other clinical clues. The frequency of this disorder is at least 1/10,000-15,000 births. Avoidance of fasting and supplementation with carnitine may be lifesaving in these patients who generally present in infancy. Salicylate Intoxication Both hyperglycemia and hypoglycemia occur in children with salicylate intoxication. Accelerated utilization of glucose, resulting from augmentation of insulin secretion by salicylates, and possible interference with gluconeogenesis may contribute to hypoglycemia. Infants are more susceptible than are older children. Ketosis may occur. Blueprint in Pediatric Endocrinology 359

Defects in Glucose Transporters Glut-1 Deficiency Two infants with a seizure disorder were found to have low cerebrospinal fluid (CSF) glucose concentrations despite normal plasma glucose. Lactate concentrations in CSF were also low, suggesting decreased glycolysis rather than bacterial infection, which causes low CSF glucose with high lactate. The erythrocyte glucose transporter was defective, suggesting a similar defect in the brain glucose transporter responsible for the clinical features. A ketogenic diet reduced the severity of seizures by supplying an alternate source of brain fuel that bypassed the defect in glucose transport. Glut-2 Deficiency Children with hepatomegaly, galactose intolerance, and renal tubular dysfunction (Fanconi-Bickel syndrome) have been shown to have a deficiency of the GLUT-2 glucose transporter of plasma membranes. In addition to liver and kidney tubules, GLUT-2 is also expressed in pancreatic β cells. Hence, the clinical manifestations reflect impaired glucose release from liver and defective tubular reabsorption of glucose plus phosphaturia and aminoaciduria. Systemic Disorders Several systemic disorders are associated with hypoglycemia in infants and children. Sepsis is often associated with hypoglycemia, possibly as a result of diminished caloric intake with impaired gluconeogenesis. Similar mechanisms may apply to the hypoglycemia found in severely malnourished infants or those with severe malabsorption. Hyperviscosity with a central hematocrit of > 65% is associated with hypoglycemia in at least 10-15% of affected infants. Falciparum malaria has been associated with hyperinsulinemia and hypoglycemia. Heart and renal failure have also been associated with hypoglycemia, but the mechanism is obscure. Diagnosis A careful and detailed history is essential in every suspected or documented case of hypoglycemia. Specific points to be noted include age at onset, temporal relation to meals or caloric deprivation, and a family history of prior infants known to have had hypoglycemia or of 360 Chapter 9: Hypoglycemia in Children and Adolescents

unexplained infant deaths. In the first week of life, the majority of infants have the transient form of neonatal hypoglycemia either as a result of prematurity versus intrauterine growth restriction or by virtue of being born to diabetic mothers. The absence of a history of maternal diabetes, but the presence of macrosomia and the characteristic large plethoric appearance of an ―infant of a diabetic mother‖ should arouse suspicion of hyperinsulinemic hypoglycemia of infancy probably due to a KATP channel defect that is familial (autosomal recessive) or sporadic; plasma insulin concentrations more than 5-10 µU/ml in the presence of documented hypoglycemia confirm this diagnosis. The presence of hepatomegaly should arouse suspicion of an enzyme deficiency; if non– glucose-reducing sugar is present in the urine, galactosaemia is most likely. In males, the presence of a Microphallus suggests the possibility of hypopituitarism, which also may be associated with jaundice in both sexes. Past the newborn period, clues to the cause of persistent or recurrent hypoglycemia can be obtained through a careful history, physical examination, and initial laboratory findings. The temporal relation of the hypoglycemia to food intake may suggest that the defect is one of gluconeogenesis, if symptoms occur 6 hour or more after meals. If hypoglycemia occurs shortly after meals, galactosaemia or fructose intolerance is most likely, and the presence of reducing substances in the urine rapidly distinguishes these possibilities. The autosomal dominant forms of hyperinsulinemic hypoglycemia need to be considered, with measurement of glucose, insulin, and ammonia, and careful history for other affected family members of any age. Measurement of IGFBP-1 may be useful; it is low in hyperinsulinemia states and high in other forms of hypoglycemia. The presence of hepatomegaly suggests one of the enzyme deficiencies in glycogen breakdown or in gluconeogenesis, as outlined in. The absence of ketonemia or ketonuria at the time of initial presentation strongly suggests hyperinsulinemia or a defect in fatty acid oxidation. In most other causes of hypoglycemia, with the exception of galactosaemia and fructose intolerance, ketonemia and ketonuria are present at the time of fasting hypoglycemia. At the time of the hypoglycemia, serum should be obtained for determination of hormones and substrates, followed by repeated measurement after an intramuscular or intravenous injection of glucagon. Hypoglycemia with ketonuria in children between ages 18 months and 5 year is most likely to be ketotic Blueprint in Pediatric Endocrinology 361

hypoglycemia, especially if hepatomegaly is absent. The ingestion of a toxin, including alcohol or salicylate, can usually be excluded rapidly by the history. Inadvertent or deliberate drug ingestion and errors in dispensing medicines should also be considered. When the history is suggestive, but acute symptoms are not present, a 24-36 hour supervised fast can usually provoke hypoglycemia and resolve the question of hyperinsulinemia or other conditions. Such a fast is contraindicated if a fatty acid oxidation defect is suspected; other approaches such as mass tandem spectrometry or molecular diagnosis, or both, should be considered. Because adrenal insufficiency may mimic ketotic hypoglycemia, plasma cortisol levels should be determined at the time of documented hypoglycemia; increased buccal or skin pigmentation may provide the clue to primary adrenal insufficiency with elevated ACTH (melanocyte-stimulating hormone) activity. Short stature or a decrease in the growth rate may provide the clue to pituitary insufficiency involving growth hormone as well as ACTH. Definitive tests of pituitary-adrenal function such as the arginine-insulin stimulation test for growth hormone, IGF-1, IGFBP-3, and cortisol release may be necessary. In the presence of hepatomegaly and hypoglycemia, presumptive diagnosis of the enzyme defect can often be made through the clinical manifestations, presence of hyperlipidemia, acidosis, hyperuricemia, response to glucagon in the fed and fasted states, and response to infusion of various appropriate precursors. Definitive diagnosis of the glycogen storage disease may require an open liver biopsy. Occasional patients with all the manifestations of glycogen storage disease are found to have normal enzyme activity. Key Points During episodes of hypoglycemia, the following should be measured: . Measurement of key substrates including plasma glucose, FFA, ß- hydroxybutyrate, lactate, total and free carnitine, and acylcarnitines . Measurement of glucoregulatory hormone including plasma insulin, C-peptide, cortisol, and growth hormone . Venous blood gas for presence of metabolic acidosis. 362 Chapter 9: Hypoglycemia in Children and Adolescents

. Serum electrolytes (for calculation of the anion gap) . Liver function tests & ammonia . Toxicology studies (salicylate, ethanol, sulfonylurea) . Metabolic screening for metabolic disorders. . First voided urine should be collected. A sample should be tested for ketones (if plasma ketones are not available) and reducing substances. The presence of non-glucose reducing substances in the urine suggests galactosaemia or hereditary fructose intolerance. Treatment Glucose Therapy If the patient is conscious and able to drink and swallow safely, a rapidly-absorbed carbohydrate (glucose tablets, glucose gel, fruit juice, or honey) should be given by mouth. However, if the hypoglycemia does not improve within 10 to 15 minutes, parenteral glucose must be administered. Infants and children with altered consciousness and/or who are unable to safely a swallow rapidly absorbed carbohydrate should be treated with intravenous dextrose. While placing the intravenous lines, subcutaneous or intramuscular glucagon should be considered. Initial bolus of dextrose, 0.25 g / kg. This is usually achieved with 2-4 ml/kg of 10 percent dextrose solution, since extravasations of higher concentrations of glucose will lead to severe tissue damage. The bolus should be administered slowly (2 to 4 ml/min), regardless of age. . The infusion is given slowly to avoid acute hyperglycemia, which can cause rebound hypoglycemia. After the bolus, plasma glucose should be maintained by an infusion of dextrose at 6 to 8 mg /kg / minute. Glucagon If intravenous access is not readily available and the patient is unable to safely swallow a rapidly absorbed carbohydrate, hypoglycemia may be treated with glucagon, given intramuscularly or subcutaneously (0.03 mg/ kg up to a maximum of 1 mg). The response is frequently transient. Thus, if the hyperinsulinemia persists, repeated administration of glucose and/or glucagon may be required. The response to glucagon also may Blueprint in Pediatric Endocrinology 363

provide diagnostic information for patients in whom the etiology of hypoglycemia is unknown. The management of persistent neonatal or infantile hypoglycemia includes increasing the rate of intravenous glucose infusion to 10-15 mg / kg /min or more, if needed. This may require a central venous or umbilical venous catheter to administer a hypertonic 15-25% glucose solution. If hyperinsulinemia is present, it should be medically managed initially with diazoxide and then somatostatin analogs. If hypoglycemia is unresponsive to intravenous glucose plus diazoxide (maximal doses up to 20 mg/kg/day) and somatostatin analogs, surgery via partial or near- total pancreatectomy should be considered. Oral diazoxide, 5-15 mg/ kg /day given in divided into 2 to 3 doses daily, may reverse hyperinsulinemic hypoglycemia but may also produce hirsutism, edema, nausea, hyperuricemia, electrolyte disturbances, advanced bone age, IgG deficiency, and, rarely, hypotension with prolonged use. A long-acting somatostatin analog (octreotide) is sometimes effective in controlling hyperinsulinemic hypoglycemia in patients with islet cell disorders not caused by genetic mutations in KATP channel and islet cell adenoma. Octreotide is administered subcutaneously every 6- 12 hour in doses of 20-50 µg in neonates and young infants. Potential but unusual complications include poor growth due to inhibition of growth hormone release, pain at the injection site, vomiting, diarrhea, and hepatic dysfunction (hepatitis, cholelithiasis). Octreotide is usually employed as a temporizing agent for various periods before subtotal pancreatectomy for KATP channel disorders. It may be particularly useful for the treatment of refractory hypoglycemia despite subtotal pancreatectomy. Total pancreatectomy is not optimal therapy, owing to the risks of surgery, permanent diabetes mellitus, and exocrine pancreatic insufficiency. Continued prolonged medical therapy without pancreatic resection if hypoglycemia is controllable is worthwhile because some children have spontaneous resolution of the hyperinsulinemic hypoglycemia. This should be balanced against the risk of hypoglycemia- induced CNS injury and the toxicity of drugs. For neonates with persistent hyperinsulinemia, subtotal or focal pancreatectomy may be needed, unless hypoglycemia can be readily controlled with long-term diazoxide or somatostatin analogs. 364 Chapter 9: Hypoglycemia in Children and Adolescents

References and Further Reading 1. Scheen AJ, Lefèbvre PJ. Reactive hypoglycaemia, a mysterious, insidious but non-dangerous critical phenomenon. Rev Med Liege [French]. 2004;59(4):237-242. 2. Palladino AA, Bennett MJ, Stanley CA. Hyperinsulinism in infancy and childhood: when an insulin level is not always enough. Clin Chem. 2008; 54(2):256-263. 3. Cornblath M, Hawdon JM, Williams AF, et al. Controversies regarding definition of neonatal hypoglycemia: suggested operational thresholds. Pediatrics. 2000; 105(5):1141-1145. De Leَn DD, Stanley CA. Mechanisms of disease: advances in diagnosis and .4 treatment of hyperinsulinism in neonates. Nat Clin Pract Endocrinol Metab. 2007; 3(1):57-68. 5. Freeze HH. Congenital disorders of glycosylation: CDG-I, CDG-II, and beyond. Curr Mol Med. 2007;7(4):389-396.

Chapter 10

Adrenal Disorders

. Introduction . Congenital Adrenal hyperplasia . CAH Forms and characteristics of different enzyme deficiencies . 21-hydroxylase deficiency . Classical CAH: salt-loser . Classical CAH: simple virilized (non salt-loser) . Non-classical CAH o Diagnosis o Treatment . Newborn screening for CAH . Prader score for genital ambiguity . Complications of CAH . Adrenal insufficiency . Causes of primary adrenal insufficiency . Adrenal hypoplasia Congenita (AHC) . Causes of secondary and tertiary adrenal insufficiency . Clinical manifestations of adrenal insufficiency o Glucocorticoid deficiency o Mineralocorticoid deficiency o Androgen deficiency . Dynamic tests o Short synacthen test o Prolonged synacthen test o Tests of ACTH secretory ability . Treatment of Adrenal insufficiency . Cushing‘s syndrome . Causes of Cushing's syndrome . Pseudocushing's syndrome . Screening of Cushing's syndrome

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. Management of Cushing‘s syndrome . Causes of Mineralocorticoid Deficiency . Primary hypoalosteronism (Aldosterone synthase) deficiency o Treatment . Mineralocorticoid resistance (Pseudohypoaldosteronism type 1, PHA1). . Pseudohypoaldosteronism Type II o Treatment . Primary hyperaldosteronism o Clinical presentation o Treatment . Pheochromocytoma o Laboratory studies o Imaging studies o Treatment

Introduction

The adrenal gland is composed of two embryologically distinct tissues, the cortex and medulla, arising from the mesoderm and neuroectoderm, respectively. Adrenal cortex consists of three anatomically distinct zones 1) The outer zona glomerulosa which is the site of mineralocorticoid production (aldosterone), regulated mainly by renin-angiotensin system, and partially by ACTH. 2) The central zona fasciculate which is responsible for glucocorticoid synthesis, regulated by ACTH. 3) The inner zona reticularis which is the site of adrenal androgen (predominantly dehydroepiandrostenedione (DHEA, DHEA sulfate and androstenedione) secretion.

Fig. (10-1): Showing Transverse Section (left) and Microscopic Section of Adrenal Cortex (left) Congenital Adrenal hyperplasia Congenital adrenal hyperplasia (CAH) is a family of inherited enzyme deficiencies that impair normal corticosteroid synthesis by the adrenal cortex. The most common enzyme deficiency is 21-hydroxylase deficiency, which accounts for over 90% of cases. CAH is an autosomal recessive disorder and the gene encoding 21-hydroxylase enzyme, CYP21A2, is mapped to the short arm of chromosome 6 (6p21.3). To date, more than 100 mutations have been described. Approximately 95% to 98% of the mutations causing 21-hydroxylase deficiency have been

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identified through molecular genetic studies of gene rearrangement and point mutations arrays. Screening studies indicate a worldwide incidence of classical 21- hydroxylase deficient CAH as 1 in 14,000 live births. Incidences vary among different populations, ranging from 1 in 600 live births in Alaska, to 1 in 5,000 live births in Saudi Arabia, to 1 in 23,000 live births in New Zealand. The prevalence frequency of non-classical 21-hydroxylase deficient CAH is considerably higher at 1 in 1,000 in white populations, with an even higher frequency among selected ethnic groups most notably, Ashkenazi Jews and Arabs due to high rates of consanguinity. The fertility rate among untreated females with non-classical CAH is reported to be 50%. CAH can be classified as either classical (virilizing and or salt- wasting types) or non-classical. Other less common enzyme deficiencies resulting in CAH include 17-alpha-hydroxylase deficiency, 3-beta hydroxysteroid dehydrogenase deficiency, and 11-beta-hydroxylase deficiency. Compensatory increase in adrenocorticotropic hormone secretion leads to overproduction of steroid precursors in the adrenal cortex, resulting in adrenal hyperplasia. Excess precursors may be converted to androgens that may result in virilization of female fetuses. The phenotype is determined by the severity of the cortisol deficiency and the nature of the steroid precursors that accumulate proximal to the enzymatic block. Excess 17-hydroxyprogesterone is then converted through androstenedione to androgens, levels of which can increase by as much as several hundred fold. Excess androgens virilizing the undifferentiated female external genitalia, ranging from mild clitoral hypertrophy to complete formation of a phallus and scrotum. In contrast, genital development in male fetuses is normal, although excess androgens cause postnatal virilization in both genders and may manifest in precocious puberty. A severe enzyme deficiency or even a complete block of enzymatic activity produces the classic form of CAH. Two thirds to three fourths of cases have salt loss, which is life threatening. It has been known that the fetal adrenal gland can be pharmacologically suppressed by maternal replacement doses of dexamethasone. Suppression can prevent masculinization of affected female fetuses in couples who are carriers of classic CAH. Differentiation of the external genitalia begins at about 7 weeks of Blueprint in Pediatric Endocrinology 369

gestation. Chorionic villus sampling has traditionally been the earliest approach for determining gender, although earlier detection should now be possible by molecular testing for Y-sequences in maternal blood. Pharmacologic therapy can be initiated before diagnosis, but therapy is continued only if the fetus is an affected female. Hundreds of fetuses have been treated successfully with prevention or amelioration of masculinization.

Fig. (10-2): Showing Steroidogenesis Pathway Deficiency of 21-hydroxylase enzyme causes insufficient cortisol production, stimulating increased production of corticotrophin-releasing hormone and ACTH. High ACTH levels lead to adrenal hyperplasia and over production of excess androgens (e.g., delta-4-androstenedione), which do not require 21-hydroxylation for synthesis. Symptoms of excessive androgens are found in varied degrees in classical and non- classical forms of 21-hydroxylase deficiency and are attributable to the severity of the enzyme defect. The internal female reproductive tract remains normal, as the ovaries do not produce anti-Müllerian hormone. Postnatal virilization includes rapid growth, premature development of pubic hair, and advanced body 370 Chapter 10: Adrenal Disorders

maturation leading to secondary precocious puberty, early epiphysis fusion, and short final adult height. Short stature may be the combined result of elevated adrenal androgens causing advanced epiphyseal maturation and premature epiphyseal fusion, with glucocorticoid overproduction inducing growth suppression, leading to short stature. Gonadal dysfunction usually occurs, as the excess adrenal androgens suppress pituitary gonadotropin and thus impair testicular growth and function. When the loss of 21-hydroxylase function is severe, adrenal aldosterone secretion is insufficient to stimulate sodium reabsorption by the distal renal tubules, resulting in salt-wasting as well as cortisol deficiency, in addition to androgen excess. CAH Forms & Characteristics of Different Enzyme Deficiencies 21-hydroxylase Deficiency Classical CAH: Salt-loser . Most severe form of the disease . Approximately 75% of cases . Commonly present with ambiguous genitalia in the female . Characterized by insufficient aldosterone, with vomiting and dehydration occurring early (1-4 weeks) in infant life and risk of life- threatening adrenal crises. Classical CAH: Simple Virilized (non salt-loser) . Enzyme defect is moderate. . Approximately 25% of cases. . Retain ability to conserve salt. Non-Classical CAH . Mild-to-moderate enzyme deficiency. . Females do not have virilized genitalia at birth. . May present in a child as precocious development of axillary hair or odor, pubic hair, acne, or tall stature as a child with an advanced bone age that may eventually result in short stature as an adult. . Adolescent females may also present with oligomenorrhoea, amenorrhea, polycystic ovaries, acne, hirsutism, or alopecia. Blueprint in Pediatric Endocrinology 371

11- β-Hydroxylase Deficiency . Hypertension (HTN) . Hyperandrogenism, causing ambiguous genitalia in female infants and childhood virilization in both sexes. 3- β-Hydroxysteroid Dehydrogenase Deficiency . Ambiguous genitalia in both males and females . Salt-wasting (rare). 17-α-Hydroxylase Deficiency . Hypertension (HTN) and hypokalemia . Delayed puberty in females and virilization in males . No salt-wasting occurs. . Antenatal diagnosis can be performed in the first trimester by molecular genetic analysis of fetal DNA from chorionic villus sampling or amniocentesis. . Dexamethasone treatment of the affected female fetus does not prevent the development of CAH, but helps in prevention of antenatal virilization in affected girls. Newborn Screening In some countries, is performed by measuring 17- hydroxyprogesterone on filter paper blood spot sample obtained by the heel-prick technique. Screening serves several important purposes: . Identifying the classical form of 21-hydroxylase CAH. . Determining patients at risk for life-threatening salt-wasting crises. . Expediting the diagnosis of females with ambiguous genitalia. . Detecting some (though not all) people with the non-classical form. Diagnosis at birth of a female usually is made immediately due to the apparent genital ambiguity. As differentiation of the external genitalia is unaffected in newborn males, only hyperpigmentation may suggest increased ACTH secretion. Diagnosis at birth in males usually depends on antenatal or newborn screening. A positive family history is common. Infertility, both male and female, is commonly identified when a couple attempts to have a child. 372 Chapter 10: Adrenal Disorders

Signs of hyperandrogenism in affected children include precocious puberty or early onset of facial, axillary, and pubic hair, adult body odor, and rapid somatic growth. This early growth spurt is accompanied by premature epiphyseal maturation and closure, resulting in a final height that is below that expected from parental heights. Patients tend to be tall children, but short adults. In adolescence and adult age, signs of hyperandrogenism may include temporal balding, severe acne, irregular menses, hirsutism, and infertility. Menstrual irregularity and secondary amenorrhea with or without hirsutism occur in a subset of post-menarche females, especially those in poor hormonal control. Primary amenorrhea or delayed menarche can occur if females with classical CAH if untreated, inadequately treated, or over treated with glucocorticoid. Infants with salt-wasting have poor feeding, weight loss, failure to thrive, vomiting, and dehydration, hypotension, hyponatraemia, and hyperkalaemic metabolic acidosis progressing to adrenal crisis (azotaemia, vascular collapse, shock, and death). Adrenal crisis can occur as early as 1 to 4 weeks of age. Non-Classical CAH A positive family history is common. Symptoms include acne, premature development of pubic hair, accelerated growth, advanced bone age, and reduced adult stature as a result of premature epiphyseal fusion. Acne tends to be severe with pustules and red papules on the face, back, and other regions of the body. Females are born with normal genitalia; postnatal symptoms may include hirsutism, temporal baldness, delayed menarche, menstrual irregularities, and infertility. Among adult females, most present with hirsutism only, with rare presentations of only hirsutism and menstrual disorder or menstrual disorder only. Males may have early beard growth and an enlarged phallus with relatively small testes. Symptoms in adult males may be limited to short stature or oligospermia and diminished fertility. Diagnosis The characteristic biochemical abnormality is an elevated serum concentration of 17-hydroxyprogesterone. False positive results from neonatal screening are common with premature infants, and many screening programs have established reference ranges that are based upon weight and gestational age. High serum androstenedione, testosterone, Blueprint in Pediatric Endocrinology 373

low 08:00 am serum cortisol level, high serum ACTH, increased urinary excretion of metabolites of cortisol precursors, particularly pregnanetriol, pregnanetriol glucuronide, and 17-ketosteroids. (Pregnanetriol and its glucuronide are the major metabolites of 17-hydroxyprogesterone, and 17-ketosteroids are metabolites of androgens). Patients with the salt- losing form have low serum concentrations of aldosterone and increased plasma renin activity. The mineralocorticoid deficiency can lead to hyponatraemia, hyperkalemia and metabolic acidosis. Patients are also at risk for hypoglycemia during an adrenal crisis. To assess borderline cases, the standard high-dose (250 mcg synacthen) test, not the low-dose (1 mcg) test, should be used. Genetic testing also can be used to evaluate borderline cases. Genetic testing detects approximately 95 % of mutant alleles. Newborns or infants with ambiguous genitalia are recommended for karotyping or FISH (fluorescence in situ hybridization) for X and Y chromosome detection, and an ultrasound of the pelvis to identify internal female genitalia and adrenal glands to look for the large size. Prader Score for Genital Ambiguity

Fig. (10-3): Showing Prader Score for Genital Ambiguity (top) and Female Neonate with Hyperpigementation and DSD due to Congenital adrenal Hyperplasia.

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Genital ambiguity can be evaluated by the Prader score in newborn females. The scores range on a scale of 1 to 5 (I to V). The genitalia can be scored from slightly virilized (score of 1) to indistinguishable from a male (score of 5). Most females with classical 21-hydroxylase deficiency are born with Prader IV genitalia. Treatment Adrenal Crisis The initial goals are treatment of hypotension and dehydration, reversal of electrolyte abnormalities, correction of metabolic acidosis and correction of cortisol deficiency. An intravenous bolus of 10 to 20 ml/kg over one hour of normal saline should be administered. An intravenous bolus of 2 to 4 ml/kg of 10 % dextrose should be considered if there is significant hypoglycemia after fluid resuscitation, the preferred type of fluid is 5 % dextrose in normal saline. Hypotonic saline should not be used because it can worsen the hyponatraemia; the same is true of 5 % dextrose without the addition of normal saline. Hyperkalemia should be corrected with the administration of glucose and insulin if necessary. Glucocorticoid is usually administered as hydrocortisone in a dose of 12 to 15 mg/m2/day. In the early phase of treatment, infants may require up to 25mg/m2/day of hydrocortisone to reduce markedly elevated adrenal hormones. This dose range exceeds the daily cortisol secretory rate of normal infants and children, which is estimated to be 7 to 9 mg/m2/day in neonates and 6 to 7 mg/m2/day in children and adolescents. There are four types of cortisol replacement treatment: Hydrocortisone, Cortisone acetate (now rarely available in some countries), Prednisolone and Dexamethasone. They vary in their dose and duration of action. Prednisolone is 5 times more potent, and dexamethasone is 40 times more potent than cortisol. Both prednisolone and dexamethasone are comparatively long acting, where as cortisone acetate and hydrocortisone are shorter acting, and need to be taken 3 times a day. The dose in each dexamethasone tablet is not convenient for fine-tuning of treatment leading to a danger of taking too high a dose. Hydrocortisone is also used as an injection at times of adrenal crisis or when vomiting prevents the tablets from being taken. For older adolescents and adults, long-acting glucocorticoid such as dexamethasone or prednisolone is the preferred treatment. When given at Blueprint in Pediatric Endocrinology 375

bedtime, these drugs effectively suppress ACTH secretion for much of the next day. However, the longer duration of action and greater potency of dexamethasone may increase the risk of over treatment, restricting linear growth if given prior to epiphyseal closure. Dexamethasone is given as a bedtime dose of 0.25 to 0.50 mg. The usual pediatric dose of fludrocortisone is 0.05 to 0.2 mg / day. Infants with the salt-losing may require higher doses of fludrocortisone (occasionally up to 0.3 mg / day) and also require sodium chloride supplementation of 1 to 3 g / day (equal to 17 to 51 meq / day) distributed in several feedings. Fludrocortisone doses may be decreased after 6 to 12 months of age because sensitivity to mineralocorticoid increases as the kidneys mature in the first year of life. . Salt tablets can be discontinued as the child begins to eat table food and the taste for salty food increases. . Additional salt intake may be needed with exposure to hot weather or with intense exercise. . Plasma renin activity immunoassays is used to monitor the adequacy of mineralocorticoid and sodium replacement, taking into account the age-specific reference ranges for each laboratory . Hypotension, hyperkalemia, and elevated renin levels suggest the need for an increase in the dose, whereas hypertension, edema, tachycardia, and suppressed plasma renin activity signify overtreatment with mineralocorticoids.

Key Points

. Prenatal treatment for CAH should be regarded as experimental. . Glucocorticoid therapy should be carefully titrated to avoid Cushing syndrome. . In infants, mineralocorticoid replacement and sodium supplementation are encouraged. . Use of agents to delay puberty and promote growth is experimental. 376 Chapter 10: Adrenal Disorders

. Children with CAH have a normal life expectancy and for most people there is very little interference in everyday life if the condition is well managed. . During infancy, initial reduction of markedly elevated adrenal sex hormones may require up to 25 mg hydrocortisone (HC)/m2·/day, but typical dosing is 12–15 mg/m2·/day divided three times daily . Hydrocortisone oral suspension is not recommended . Divided or crushed tablets of Hydrocortisone should be used in growing children . The goal of therapy in CAH is to both correct cortisol deficiency and to suppress ACTH overproduction. . There are four types of cortisol replacement: Hydrocortisone, Cortisone acetate (now rarely available in some countries), Prednisolone and Dexamethasone. They vary in their dose and duration of action. Prednisolone is 5 times more potent, and dexamethasone is 40 times more potent than cortisol. Both prednisolone and dexamethasone are comparatively long acting, where as cortisone acetate and hydrocortisone are shorter acting, and need to be taken 3 times a day. . Whereas HC is preferred during infancy and childhood, long- acting glucocorticoids may be an option at or near the completion of linear growth.

. Prednisolone need to be given twice dailyThe dose (2–4 mg/m2 /day) which is approximately one fifth the dose of HC. . Dosage requirements for patients with non classical CAH may be less. . A small dose of dexamethasone at bedtime (0.25–0.375 mg/m2·d) (0.25 to 0.5 mg) is usually adequate for androgen suppression in non- classical patients. . Anti-androgen treatment may be useful as adjunctive therapy in adolescent females who continue to have hyperandrogenic signs despite good adrenal suppression. Blueprint in Pediatric Endocrinology 377

. Females with concomitant PCOS may benefit from an oral contraceptive, though this treatment would not be appropriate for patients trying to get pregnant. . Over-treatment should be avoided because it can lead to Cushing syndrome. . Depending on the degree of stress, stress dose coverage may require doses of up to 50-100 mg/m2/day, and should be continued as far as stress is present, there is no time limit. Stress Dosing of Glucocorticoid During periods of stress (surgery, febrile illness, shock), all patients with classical CAH require increased amounts of glucocorticoid. Typically, 2 to 3 times the normal dose is administered orally, or by intramuscular injection when oral intake is not tolerated or and if there is vomiting or diarrhea. Up to 5 to 10 times the daily dosage may be required during surgical procedures. Affected patients should always carry information regarding corticosteroid dosing to alert and inform healthcare personnel in case of emergency. The mineralocorticoid dose does not need to be increased during stress. . During periods of stress (surgery, febrile illness, shock), all patients with classical CAH require increased amounts of glucocorticoid. . Typically, 2 to 3 times the normal dose is administered orally, or by intramuscular injection when oral intake is not tolerated or and if there is vomiting or diarrhea. . Up to 5 to 10 times the daily dosage may be required during surgical procedures. . The mineralocorticoid dose does not need to be increased during stress. . Dose of intravenous bolus of 50-100 mg/m2 stat followed by 100 mg/m2/ day divided into 4 doses. Feminizing Genitoplasty In females with classical CAH who are virilized at birth, feminizing genitoplasty may be performed to remove the redundant erectile tissue while preserving the sexually sensitive glans clitoris. This procedure also 378 Chapter 10: Adrenal Disorders

intends to provide a normal vaginal orifice that functions adequately for menstruation, intercourse and delivery. Clitoroplasty is typically performed in early childhood (preferably at age 6 to 18 months). When necessary, vaginoplasty is usually performed in late adolescence because routine vaginal dilation is required to maintain a patent vagina. Adrenalectomy Bilateral adrenalectomy has been reported as an experimental treatment of patients with severe disease who are homozygous for two null mutations and who have a history of poor control with hormonal replacement therapy. This procedure is done only rarely. It is important to note that recurrence of increased serum concentration of adrenal corticosteroid hormones has been observed in some females undergoing adrenalectomy. The elevated serum concentration of adrenal corticosteroids is thought to result from the presence of ectopic adrenal rests (tumors) in the ovaries. More long-term data are needed to determine the significance and frequency of the rests in these women. Monitoring . Successful treatment of affected children hinges on the delicate balance of suppressing adrenal androgen secretion with glucocorticoid administration while maintaining normal growth. . In growing children, follow-up is usually every 3 months. . In adolescents, follow-up can be spaced to every 6 to 12 months. . Growth data, pubertal assessment, and blood pressure measurements are necessary for each visit. . Serum concentrations of 17-hydroxyprogesterone, delta-4- androstenedione, dehydroepiandrosterone, testosterone and renin are monitored every 6 months. . Bone maturation is assessed by bone age of the left hand, usually annually. . In adolescents, bone mineral density to assess bone strength and imaging of the gonads to assess adrenal rest tumors are performed periodically. Blueprint in Pediatric Endocrinology 379

. 17-OHP should not return to normal for age levels, but being kept in a reasonable range in the morning before the first therapeutic doses (30–100 nmol/l) . Testosterone is also a very useful parameter in females at all ages, and in prepubertal boys, and contrary to 17-OHP should be maintained in the normal range for age . In pubertal females, androstenedione and LH/FSH should be monitored because of the risk of developing polycystic ovaries . In pubertal males, testosterone and LH/FSH indicate whether treatment is well controlled, because increased adrenal androgens may suppress the pituitary gonadotropin . CAH is associated with short stature in adults even when optimal adrenal hormonal control is maintained throughout childhood and puberty . Dosing is determined and delivered by an endocrinologist familiar with the use of these hormones . Short stature in adulthood due to excess androgens causing precocious puberty and advanced bone age . Optimum glucocorticoid replacement therapy and in some cases a combination treatment of growth hormone and GnRH analogues results in improved final height and reduction of the early onset of puberty, but it is considered experimental Complications Adrenal crisis is characterized by azotaemia, vascular collapse, shock, and death. This can occur as early as 1 to 4 weeks of age. An intravascular injection of hydrocortisone with intravenous fluids containing dextrose and saline should be given immediately. Hydrocortisone dose adjustment depends on patient's symptoms and signs of androgen excess, steroid measurements, and growth and development all need to be considered. Precocious puberty is most likely to develop when the diagnosis of CAH is delayed or when adrenal androgen secretion is poorly controlled; such patients may benefit from treatment with gonadotropin-releasing hormone analog. 380 Chapter 10: Adrenal Disorders

Testicular adrenal rests (benign tumors) are most often seen in male patients with classical salt-wasting CAH who are inadequately treated. Deficient spermatogenesis is also found. Imaging with MRI or ultrasound plus biopsies can confirm the benign nature of the tumor. Treatment with glucocorticoid replacement therapy will usually cause reduction in the masses, but testis-sparing surgery or orchidectomy may be required. CAH is associated with short stature in adults even when optimal adrenal hormonal control is maintained throughout childhood and puberty. It has been shown that growth hormone therapy, alone or in combination with a gonadotropin-releasing hormone analogue, is effective in improving growth rate, height deficit, and final height in children. Dosing is determined and delivered by an endocrinologist familiar with the use of these hormones. Short stature due to excess androgens cause precocious puberty and advanced bone age. optimum glucocorticoid replacement therapy and in some cases a combination treatment of growth hormone and GnRH analogues results in improved final height and reduction of the early onset of puberty. . Patients, who are compliant to medications, will maintain healthy, normal lives. . Patients who are non-compliant will suffer many of the signs and symptoms of hyperandrogenaemia. . Poor compliance with medication can also lead to a potentially fatal addisonian crisis. Key points . CAH is a group of autosomal recessive disorders characterized by a defect in one of the enzymes required in the synthesis of cortisol from cholesterol. . Cortisol deficiency results in over secretion of ACTH and hyperplasia of the adrenal cortex. . CAH is the most common cause of ambiguous genitalia in females. . 21-Hydroxylase deficiency accounts for 90% of cases. . The enzymatic defect results in impaired synthesis of adrenal steroids beyond the enzymatic block and overproduction of the precursors before the block. Blueprint in Pediatric Endocrinology 381

Classic Form (Complete Enzyme Deficiency) . Occurs with or without salt loss, symptoms occur in the absence of stress, adrenal crisis in untreated patients occurs at 1 to 2 weeks of life, with signs and symptoms of adrenal insufficiency rarely occurring before 3 to 4 days of life. (Non-salt-losing forms have a less severe risk for adrenal crisis owing to preservation of mineralocorticoid synthesis.). . Elevated 17-hydroxyprogesterone (17-OHP) levels (often on newborn screen) with elevated testosterone in girls and androstenedione in boys and girls . The dose of glucocorticoid should be increased in patients with fever or illness to mimic normal physiologic cortisol response to stress dose of 50 - 100 mg /m2 /day of hydrocortisone intravenous or intramuscular. . For surgery or severe illness, hydrocortisone doses of 50–100 mg/ m2/day intravenous /intramuscular may be indicated. Non –Classical CAH (NCAH) It is a common autosomal recessive disorder. Higher prevalences have been reported in Ashkenazi Jewish, Mediterranean, Middle-Eastern and Indian populations. Reported gene frequencies vary among ethnic groups and geographic region. The clinical features predominantly reflect androgen excess rather than adrenal insufficiency leading to an ascertainment bias favoring diagnosis in females. Treatment goals include normal linear growth velocity and ―on-time‖ puberty in affected children. For adolescent females treatment goals include regularization of menses, prevention of progression of hirsutism, and fertility. Individuals with NCAH generally present with signs and symptoms of androgen excess rather than symptoms reflecting glucocorticoid deficiency. Children may present with premature pubarche (i.e. the development of pubic hair, axillary hair, and/or increased apocrine odor prior to age 8 years in girls and age 9 years in boys). Additional features in children include tall stature, accelerated linear growth velocity, and advanced skeletal maturation. Examination of the external genitalia may reveal clitoral enlargement in some girls without genital ambiguity. Phallic enlargement with prepubertal testes may be noted in boys. Although tall as children, the accelerated skeletal maturation promotes 382 Chapter 10: Adrenal Disorders

premature epiphyseal fusion leading to short stature in adulthood. Typically, these symptoms are more prominent among children with classic CAH. During adolescence and adulthood, an ascertainment bias favors the diagnosis in females due to the nature of the hyperandrogenic symptoms which include hirsutism, acne, alopecia, anovulation, and menstrual dysfunction and decreased fertility, however, not all individuals with NCAH will be symptomatic. Diagnosis In general, newborn screening programs fail to detect individuals with NCAH. Newborn screening programs measure of 17-OHP in whole blood spots collected on filter paper. The 17-OHP results for infants with NCAH are often not as elevated as those for infants with classic CAH. Given the comparatively mild course of NCAH during childhood and the anxiety and costs involved in false positive results, treatment based solely on elevated hormone levels in the absence of symptoms may only increase the risk for iatrogenic adrenal insufficiency without any clear therapeutic benefit. Thus, risk/benefit analysis of confirming the diagnosis of NCAH in a neonate prior to the development of symptoms is unresolved due to the lack of outcome data. The clinical features of NCAH in post pubertal adults may be difficult to differentiate from those of the polycystic ovary syndrome (PCOS) or, in children, from premature adrenarche. Although random 17-OHP concentrations are usually diagnostic in classical forms of CAH, random 17-OHP concentrations may be within the normal range for individuals with NCAH. Thus, the acute ACTH stimulation test remains the gold standard to confirm decreased 21-hydroxylase activity. Following collection of a blood sample to measure baseline hormone concentrations, synthetic ACTH (Synacthen, 0.25 mg) is administered. A second blood sample is collected 30–60 minutes later. Genetic testing should not be considered a first-line diagnostic study in individuals suspected of NCAH. Treatment Clinical goals of treatment include normal linear growth velocity, normal rate of skeletal maturation, ―on-time‖ puberty, and appropriate weight status for children and adolescents. For adolescent females, goals of therapy include regularization of menstrual cycles, prevention of Blueprint in Pediatric Endocrinology 383

progressive hirsutism and acne, and fertility. For each child, adolescent, and adult with NCAH, the benefits of treatment should be weighed against the potential risks of acute adrenal insufficiency secondary to iatrogenic adrenal suppression due to glucocorticoid treatment. Treatment of hirsutism may also necessitate adjunctive cosmetic methods such as laser, electrolysis, and depilatories. Glucocorticoid treatment can be utilized for children and adolescents with significantly advanced skeletal maturation. Although treatment with oral contraceptives alone may be sufficient in oligomenorrheic, acneic, or mildly hirsute adolescents and adult women not seeking fertility, early glucocorticoid treatment may be beneficial to decrease the risk of persistent anovulation. The use of anti-androgens (e.g. flutamide, Cyproterone acetate, or finasteride) should also be considered in women complaining of excess unwanted hair growth or scalp hair loss (androgenic alopecia). Despite minimal changes in testosterone and androstenedione concentrations, greater improvement in hirsutism was noted with the use of Cyproterone acetate compared to hydrocortisone among women with NCAH. Thus, for adolescent and adult women with NCAH who are taking glucocorticoids, the addition of oral contraceptives or anti-androgens may allow for lower glucocorticoid dosage. One effective regimen involves hydrocortisone, 6–15 mg/m2/day divided into three daily doses. Many clinicians suggest that reverse circadian dosing with the highest hydrocortisone dose at night provides improved control, but no consensus exists regarding how to divide the doses. All individuals on glucocorticoid therapy require instruction regarding stress doses, including parenteral therapy, and should wear medical alert identifying badges. For daily treatment, prednisone, prednisolone, or dexamethasone may also be used in adults. As the androgen secretory potential of the adrenal cortex declines with age, the demand for glucocorticoids to suppress adrenal androgen secretion in NCAH may ameliorate with age. Stress doses of hydrocortisone are essential for affected individuals maintained on glucocorticoid treatment. For emergency situations, including labor and delivery and surgery, the empiric stress dose is parenteral hydrocortisone (Solu-Cortef), 100 mg, intravenous or intramuscular. 384 Chapter 10: Adrenal Disorders

. Non-classical congenital adrenal hyperplasia is a common autosomal recessive disorder that can present in childhood, adolescence, and adulthood. . The typical symptoms of hirsutism, oligomenorrhoea, infertility, acne, and premature pubarche lead to an ascertainment bias in favor of identifying affected women. . The nature of the symptoms leads to consideration of polycystic ovary syndrome in the differential diagnosis. . Although NCAH is a genetic disorder, the use of morning 17-OHP concentrations and ACTH stimulation tests are essential diagnostic studies. . Once the diagnosis is confirmed, genetic analysis may be useful. The specific treatment should be individualized and directed towards the individual's symptoms and current medical needs. Adrenal Insufficiency Adrenal insufficiency is defined by the impaired synthesis and release of adrenocortical hormones. It is classified based upon whether the etiology is primary, secondary, or tertiary. . Primary adrenal insufficiency results from disease intrinsic to the adrenal cortex. . Secondary adrenal insufficiency is caused by either impaired release or effect of adrenocorticotropic hormone (ACTH) from the pituitary gland. . Tertiary adrenal insufficiency results from the impaired release or effect of corticotropin releasing factor from the hypothalamus. . In addition, disorders of end-organ unresponsiveness to ACTH hormone that present in a similar manner as diseases caused by adrenocortical hormone deficiencies. Causes of Primary Adrenal Insufficiency . Addison's disease, which could be an isolated disease or associated with Polyendocrinopathy syndrome. Adrenal insufficiency is the result of an autoimmune process that destroys the adrenal cortex. Approximately 90% of the adrenal cortex needs to be destroyed to produce adrenal Blueprint in Pediatric Endocrinology 385

insufficiency. Both humoral and cell-mediated immune mechanisms directed at the adrenal cortex are involved. Antibodies that react with several steroidogenic enzymes as well as all three zones of the adrenal cortex are detected in 60-75% of patients with autoimmune primary adrenal insufficiency. Approximately 50% of patients with autoimmune adrenal insufficiency have one or more other autoimmune endocrine disorders, whereas patients with the more common autoimmune endocrine disorders, such as type 1 diabetes mellitus, chronic autoimmune thyroiditis, or Graves' disease, rarely develop adrenal insufficiency. Combination of autoimmune adrenal insufficiency with other autoimmune endocrine disorders is referred to as the autoimmune polyglandular syndrome APS1 and APS2. . APS1, known as autoimmune polyendocrinopathy-candidiasis- ectodermal dystrophy (APECED), includes hypoparathyroidism, chronic mucocutaneous candidiasis, and adrenal insufficiency. Other findings include primary hypogonadism and malabsorption. . APS2 has primary adrenal insufficiency, with additional autoimmune thyroiditis and type 1 diabetes mellitus. APS2 is more prevalent than type 1. The age of onset ranges from childhood to late adulthood with most cases presenting between 20 to 40 years of age. . Infectious adrenalitis: Tuberculosis is the second most common cause of primary adrenal insufficiency. Less common causes include meningococcal infection, systemic fungal infections (histoplasmosis and paracoccidioidomycosis), and opportunistic infections secondary to HIV infection. . Congenital adrenal hyperplasia.(mentioned above) . Congenital adrenal aplasia/hypoplasia which could be an autosomal recessive due to SF 1 gene mutation or sex linked recessive disease due to DAX 1 gene mutations associated with hypogonadism and can be linked with contiguous genes at Xp21.2 including Duchene's and glycerol kinase deficiency. . Bilateral adrenal infarction caused by hemorrhage or adrenal vein thrombosis may also lead to adrenal insufficiency. Adrenal hemorrhage has been mostly associated with meningococcemia (Waterhouse- Frederickson syndrome) and Pseudomonas aeruginosa infection. 386 Chapter 10: Adrenal Disorders

. Certain drugs may cause adrenal insufficiency by inhibiting cortisol biosynthesis include antiepileptic, ketoconazole and metyrapone. Drugs that accelerate the metabolism of cortisol such as phenytoin, barbiturates, and rifampicin can cause adrenal insufficiency in patients with limited pituitary or adrenal reserve and those on glucocorticoid replacement therapy. . Peroxisomal disorders are a heterogeneous group of inborn errors of metabolism, either result from a defect in a single peroxisomal enzyme or from abnormal peroxisomal biogenesis affecting multiple peroxisomal functions. Neurological impairment in most of peroxisomal disorders. The adrenal gland is involved in adrenoleukodystrophy (ALD), neonatal ALD, Refsum disease, and Zellweger syndrome).in peroxisomal diseases caused by mutations of the ATP-Binding Cassette, Subfamily D, Member 1 gene (ABCD1 gene). These mutations prevent normal transport of very long chain fatty acids (VLCFA) into peroxisomes, thereby preventing beta-oxidation and breakdown of VLCFA. Accumulation of abnormal VLCFA in affected organs (central nervous system, Leydig cells of the testes, and the adrenal cortex), is presumed to be the underlying pathologic process of these disorders. In almost all cases, adrenocortical failure occurs along with irreversible degenerative neurologic defects. Adrenal failure may predate, occur simultaneously with, or follow the onset of the neurologic deterioration. Adrenal Hypoplasia Congenita (AHC) AHC results from mutations in the DAX-1 gene (dose-sensitive sex- reversal) on the short arm of X chromosome (Xp21). In AHC, both cortisol and aldosterone secretion are reduced because of impaired development of the definitive zone in the first trimester of gestation. DAX-1 is expressed in the adrenal cortex, gonads, hypothalamus and pituitary gland. Children with AHC present as neonates (1 to 4 weeks of age), the age and severity of the disease can vary. Some individuals present later in childhood. Clinical manifestations include the following: Affected neonates most often present with signs and symptoms of salt-losing crisis similar to that of CYP21A2 (21-hydroxylase) deficiency including hyponatraemia, hyperkalemia, hypovolemia, and hypotension. Patients have low serum cortisol and aldosterone levels, and elevated plasma ACTH levels as well as hyperpigmentation. Hypogonadotropic Blueprint in Pediatric Endocrinology 387

hypogonadism occurs in surviving affected males treated with replacement steroids, prepubertal gonadal development is normal, but pubertal development is impaired, resulting in hypogonadism. The site of the defect appears to be within the hypothalamic-pituitary-gonadal axis. Xp21 contiguous gene complex DAX-1 gene is contiguous with the dystrophin (Duchene muscular dystrophy) and glycerol kinase (juvenile glycerol kinase deficiency) genes on the short arm of the X chromosome. There are case reports of patients with deletions of this complex who present with adrenal insufficiency, muscular dystrophy, and intellectual disability (mental retardation). Other features include short stature, testicular abnormalities (cryptorchidism and /or hypogonadism), and peculiar facies (drooping mouth and wide-set eyes). Steroidogenic factor-1 (SF-1) gene maps to chromosome 9q33. SF-1 regulates tissue-specific expression of cytochrome P450 steroid hydroxylases and is expressed in the gonads, adrenal glands, anterior pituitary gland, and hypothalamus. SF-1 interacts with DAX-1, and is important in both male sexual differentiation and adrenal gland development. Case reports of mutations of SF-1 describe male to female sex reversal with ambiguous genitalia noted at birth in affected males. Patients also present as neonates with signs and symptoms of salt-loss similar to those with DAX-1 mutations. Other patients with SF-1 mutations have disorders of sex development but no adrenal abnormalities IMAGe Syndrome It is characterized by intrauterine growth retardation, metaphyseal dysplasia, adrenal hypoplasia congenita, and genital anomalies. The cause is unknown and reported cases do not have either DAX-1 or SF-1 mutations. X-linked inheritance (inheritance from maternal line) is suspected in some pedigrees, and both affected males and females have been described. Familial Glucocorticoid Resistance It is a rare hereditary disorder resulting from mutations in the glucocorticoid receptor gene. It is characterized by unresponsiveness of targeted end-organs to the actions of cortisol. Although there are high circulating levels of cortisol, the glucocorticoid receptor defect results in clinical manifestations similar to those with glucocorticoid deficiency. 388 Chapter 10: Adrenal Disorders

Triple A Syndrome It is composed of ACTH-resistant cortisol deficiency, achalasia, and absent lacrimation have the triple A syndrome or Allgrove syndrome. This is an autosomal recessive disorder resulting from a defect in the AAAS gene located on chromosome 12q13. Many of these patients have neurologic disorders including peripheral, autonomic, and central nervous system impairments. Some also have a mild defect in mineralocorticoid (aldosterone) secretion, particularly when salt restricted. Key Points . Primary adrenal insufficiency is defined as the impaired synthesis and /or release of adrenocortical hormones on account of disease intrinsic to the adrenal cortex. . Clinical manifestations are dependent on the type of hormonal class affected and the severity of the defect(s). . The hormones are divided into glucocorticoid (cortisol), mineralocorticoid (aldosterone), and adrenal androgens (dehydroepiandrosterone). . Adrenal crisis or acute adrenal insufficiency can be observed as the initial presentation of adrenal insufficiency or as the result of inadequate replacement therapy in patients with known adrenal insufficiency. . To minimize morbidity and mortality, prompt recognition and treatment of adrenal crisis is critical. Causes of Secondary & Tertiary Adrenal Insufficiency . Post pharmacologic glucocorticoid therapy. . Pituitary disorders (congenital hypopituitarism, tumors e.g. craniopharyngioma). . Hypothalamic disorders. Secondary adrenal insufficiency may be caused by any disease process that affects the anterior pituitary and interferes with ACTH secretion. ACTH deficiency may be isolated or occur in association with other pituitary hormone deficits. On the other hand, tertiary adrenal insufficiency can be caused by any process that involves the Blueprint in Pediatric Endocrinology 389

hypothalamus and interferes with CRH secretion. The most common causes of tertiary adrenal insufficiency are abrupt cessation of high-dose glucocorticoid therapy and treatment of Cushing's syndrome. Clinical Manifestations of Adrenal Insufficiency Adrenal crisis or acute adrenal insufficiency may complicate the course of chronic primary adrenal insufficiency, and may be precipitated by a serious infection, acute stress, bilateral adrenal infarction or hemorrhage. It is rare in patients with secondary or tertiary adrenal insufficiency. The main clinical manifestation of adrenal crisis is shock, but patients may also have nonspecific symptoms such as anorexia, nausea, vomiting, abdominal pain, weakness, fatigue, lethargy, confusion or coma. Hypoglycemia is rare in acute adrenal insufficiency, but more common in secondary adrenal insufficiency. Hypoglycemia is a common manifestation in children and thin women with the disorder. Hyperpigmentation due to chronic ACTH hypersecretion and weight loss are indicative of long-standing adrenal insufficiency, while additional symptoms and signs relating to the primary cause of adrenal insufficiency may also be present. Patients with secondary or tertiary adrenal insufficiency usually have normal mineralocorticoid function. Glucocorticoid Deficiency Clinical findings associated with glucocorticoid deficiency (cortisol) include fasting hypoglycemia, increased insulin sensitivity, muscle weakness, and morning headache. As a secondary consequence of cortisol deficiency, there also is increased production of pro- opiomelanocortin (ACTH precursor); this results in increased melanin synthesis, causing hyperpigmentation. This is most conspicuous in areas exposed to sunlight or pressure (elbows and knees) and also is prominent in the areas not typically exposed to sun, such as palmer creases, axilla, and gingiva. Mineralocorticoid Deficiency Clinical findings primarily result from sodium loss. These include hypotension, dizziness, salt-craving, weight loss, anorexia, and electrolyte abnormalities (hyponatraemia, hyperkalemia, and metabolic acidosis).

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Androgen Deficiency Clinical findings of adrenal androgen deficiency include decreased axillary and pubic hair as well as a loss in libido. By comparison, changes are unusual in males as most of their androgen production occurs in the testes. Prepubescent children with adrenal androgen deficiency are most commonly asymptomatic. Diagnosis The diagnosis of adrenal insufficiency depends upon the demonstration of inappropriately low cortisol secretion. Serum cortisol concentrations are normally highest in the early morning hours (04:00h - 08:00h) and increase further with stress. Serum cortisol concentrations determined at 08:00h of less than 3 µg/dl (80 nmol/l) are strongly suggestive of adrenal insufficiency, while values below 10 µg/dl (275 nmol/L) make the diagnosis likely. Basal urinary cortisol and 17- hydroxycorticosteroid excretion is low in patients with severe adrenal insufficiency, but may be low-normal in patients with partial adrenal insufficiency. Generally, baseline urinary measurements are not recommended for the diagnosis of adrenal insufficiency. Primary adrenal insufficiency is diagnosed if ACTH levels are high in the setting of low cortisol, with hyponatraemia/hyperkalemia, or with an abnormal rapid ACTH stimulation test. Other common features are laboratory evidence of mineralocorticoid deficiency (low fasting glucose, hyponatraemia, and hyperkalemia) and elevated plasma renin activity or renin concentration. Confirmation of the diagnosis requires stimulation of the adrenal glands with exogenous ACTH. Secondary or tertiary adrenal insufficiencies are diagnosed if ACTH levels are low in the setting of low cortisol. Dynamic Tests If static tests suggest adrenal insufficiency, then dynamic tests often are used to determine the level of the defect (whether it is a defect intrinsic to the adrenal gland or if the cortisol deficiency is the result of ACTH deficiency) Short Synacthen Test Used for assessing cortisol production (ACTH responsiveness) in a patient with adrenal insufficiency. In this test, serum cortisol levels are Blueprint in Pediatric Endocrinology 391

measured before and 60 minutes after the rapid intravenous infusion of synthetic ACTH. A subnormal response in a patient who has not received glucocorticoid therapy may indicate primary adrenal failure. The result of the short synacthen stimulation test is also abnormal in most patients with secondary ACTH deficiency because chronic lack of ACTH impairs the ability of the adrenal cortex to respond to acute ACTH administration, and is thus unable to produce cortisol. Such patients do not have a significantly elevated ACTH level, and have normal mineralocorticoid status. In this case, ACTH secretory ability can be accessed directly with a glucagon stimulation test or insulin-induced hypoglycemia. Prolonged Synacthen Test On rare occasions, the results of insulin-induced hypoglycemia or glucagon stimulation tests are equivocal. In these cases, a prolonged ACTH test (three days of prolonged ACTH infusions, or IM ACTH) may be indicated. The prolonged ACTH test also may be useful in differentiating between primary adrenal unresponsiveness to ACTH and low cortisol due to secondary or tertiary adrenal insufficiency, in cases when the baseline ACTH level is not below normal (a rare situation). Tests of ACTH Secretory Ability If static tests and ACTH stimulation test suggest hypopituitarism (low 8 am cortisol and low ACTH) and if further confirmation is needed, then the next step is to assess ACTH secretion with one or more dynamic tests. Several dynamic tests can be used for this purpose. Insulin-induced hypoglycemia is the most sensitive standard test of ACTH release. Serial measurements of blood glucose and cortisol are made before and at 15, 30, 45, and 60 minutes after an infusion of insulin (0.05 units / kg). The peak cortisol level should be at least double the baseline level or greater than 20 mcg/dl. If desired, samples for growth hormone can be obtained at the same time. A normal GH response is usually defined as a peak of ≥ 10 mcg/L. Symptomatic hypoglycemia is desirable during the test, but marked changes in levels of consciousness or blood glucose less than 30 mg / dl must be treated with prompt administration of intravenous dextrose. The test is not recommended for children younger than three years old because of the risk of damage to the central nervous system resulting from hypoglycemia. 392 Chapter 10: Adrenal Disorders

Glucagon stimulation test is more appropriate in children younger than three years. After an intramuscular injection of glucagon, the blood glucose level initially raises then drops rapidly because of the release of endogenous insulin. Serum cortisol and growth hormone levels should increase in response to this fall in blood glucose Metyrapone test is used in the assessment of ACTH secretory ability, but is rarely used clinically. Metyrapone blocks the activity of the enzyme 11-beta-hydroxylase, which is needed to convert 11- deoxycortisol to cortisol, causing a decrease in serum cortisol levels. In a normal patient, the decrease in cortisol levels will stimulate ACTH secretion and increase the production of cortisol precursors. This can be measured by a rise in serum levels of ACTH and 11-deoxycortisol and/or in urinary 17-hydroxycorticosteroids and free cortisol. The ACTH- stimulated gland eventually overrides the enzymatic block, allowing cortisol production to occur. However, patients must be observed closely during this test, because acute adrenal insufficiency may be precipitated if the patient has marked ACTH deficiency. CRH stimulation test is used to differentiate between secondary and tertiary adrenal insufficiency. In both conditions cortisol levels are low at baseline and remain low after CRH. In patients with secondary adrenal insufficiency, there is little or no ACTH response, whereas in patients with tertiary disease there is an exaggerated and prolonged response of ACTH to CRH stimulation, which is not followed by an appropriate cortisol response. Key points . Adrenal insufficiency is suspected on the basis of clinical symptoms, which may include fatigue, nausea and vomiting. . Patients with primary adrenal insufficiency often have signs of mineralocorticoid deficiency, including hypotension, dehydration, and electrolyte abnormalities, and may present in adrenal crisis. . Primary adrenal insufficiency is caused by disease of the adrenal cortex. . Secondary or tertiary adrenal insufficiency are caused by impaired release or effect of ACTH from the pituitary gland or of CRH from the hypothalamus, respectively Blueprint in Pediatric Endocrinology 393

. Primary adrenal insufficiency is diagnosed if ACTH levels are high in the setting of low cortisol, with hyponatraemia/hyperkalemia, or with an abnormal short ACTH stimulation test. . Secondary or tertiary adrenal insufficiency are diagnosed if ACTH levels are low in the setting of low cortisol . A variety of dynamic tests are used to further evaluate findings of the static tests. If initial cortisol results are indeterminate, one of the tests for ACTH secretory ability (using insulin-induced hypoglycemia, glucagon, or metyrapone) will establish whether pituitary insufficiency is present. If initial static ACTH tests are low, then these tests will determine if the adrenal insufficiency is secondary or tertiary . In the case of primary adrenal insufficiency, adrenal androgens should be measured to evaluate for congenital adrenal hyperplasia. This is the most common cause of primary adrenal insufficiency but usually presents during infancy. Antibodies to the adrenals and other endocrine glands may establish an autoimmune mechanism. . Children with secondary adrenal insufficiency have deficient ACTH secretion from the pituitary; other pituitary hormones also should be measured. Treatment Adrenal crisis is a life-threatening emergency that requires immediate treatment. The aim of initial management in adrenal crises is to treat hypotension, and to reverse the electrolyte abnormalities and cortisol deficiency. Dextrose with normal saline solution should be given intravenously. The glucocorticoid deficiency should be treated by immediate intravenous administration of hydrocortisone. Once the initial treatment is offered, the cause of the adrenal crisis should be sought and treated. Once the patient's condition is stable, and the diagnosis has been confirmed, parenteral glucocorticoid therapy should be tapered over 3-4 days and converted to an oral maintenance dose. Patients with primary adrenal insufficiency require lifelong glucocorticoid and mineralocorticoid replacement therapies. Patients with adrenal insufficiency should be treated with hydrocortisone, the natural glucocorticoid. The hydrocortisone daily dose is (10-15 mg / m2/day) 394 Chapter 10: Adrenal Disorders

and can be given in two to three divided doses. A longer-acting synthetic glucocorticoid such as prednisolone, or dexamethasone, may be employed after the child growth is completed. During minor illnesses or surgical procedures, the dosage of glucocorticoid can be increased up to three times the usual maintenance dosage for three days. Depending on the nature and severity of the illness, additional treatment may be required. During major illness or surgery, high doses of glucocorticoid up to 5-10 times the daily production are required to avoid an adrenal crisis. A continuous infusion of 10 mg of hydrocortisone per hour eliminates the possibility of glucocorticoid deficiency. This dose can be halved the second postoperative day, and the maintenance dosage can be resumed the third postoperative day. Mineralocorticoid replacement therapy is required to prevent sodium loss, intravascular volume depletion, and hyperkalemia. It is given in the form of fludrocortisone in a dose of 0.1 mg daily. The dose of fludrocortisone is titrated individually on the basis of the clinical examination (mainly the body weight and arterial blood pressure) and the levels of plasma rennin activity. The mineralocorticoid dose may have to be increased in the summer, and advised to increase water and salt to avoid electrolyte disturbances and dehydration. Androgen replacement: In female adolescents, the adrenal cortex is the primary source of androgen in the form of dehydroepiandrosterone and dehydroepiandrosterone sulfate. Their replacement is being increasingly considered in the treatment of adrenal insufficiency. In chronic secondary or tertiary adrenal insufficiency, glucocorticoid replacement is similar to that in primary adrenal insufficiency, however, measurement of plasma ACTH concentration cannot be used to titrate the optimal glucocorticoid dose. Mineralocorticoid replacement is rarely required, while replacement of other anterior pituitary deficits might be necessary. Key Points . An important aspect of the management of chronic primary adrenal insufficiency is patient and family education. . Patients should understand the reason for life-long replacement therapy. Blueprint in Pediatric Endocrinology 395

. Need to increase the dose of glucocorticoid during minor or major stress and to inject hydrocortisone in emergencies. Cushing’s Syndrome Cushing syndrome is a rare disorder with an incidence of 2 to 3 cases/ million /year and only 10-20% of cases occur in childhood and adolescence. Unlike adults, where Cushing syndrome has female gender preponderance, there is no sex predilection in childhood cases and adrenal carcinomas most often occur in childhood cases of Cushing syndrome. Cushing‘s syndrome results from chronic exposure to excessive levels of glucocorticoid. It is considered rare condition; the clinical spectrum of the disease is broad. Classical signs and symptoms were described by "Harvey Cushing" early in the last century. In its severe form and when untreated, the metabolic upset of Cushing's syndrome is associated with a high mortality, approximately 50% at five years. Excesses of cortisol may have significant effects on glycaemic control and blood pressure, and pathological obesity.

Fig. (10-4): Showing Adolescent Girl with Cushing syndrome

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Causes of Cushing's syndrome Cushing's syndrome may be either ACTH-dependent or - independent. ACTH-Dependent The causes are associated with bilateral adrenocortical hyperplasia: . Cushing's disease (pituitary hypersecretion of ACTH) in 65 to 70% of cases . Ectopic secretion of ACTH by non pituitary tumors in 10 to 15% of cases. . Ectopic secretion of corticotrophin-releasing hormone (CRH) by non hypothalamic tumors causing pituitary hypersecretion of ACTH in less than 1 % of cases. . Iatrogenic or factitious Cushing's syndrome due to administration of exogenous ACTH in less than 1 % of cases. ACTH-Independent The causes are: . Iatrogenic Cushing's syndrome, which is by far the most common cause; it is usually ACTH-independent and caused by the exogenous administration of glucocorticoid, usually for their anti-inflammatory effects. . Adrenocortical adenomas and carcinomas in 20 %. . Primary pigmented nodular adrenocortical disease, also called bilateral adrenal micronodular hyperplasia in less than 1 % . Bilateral ACTH-independent macronodular hyperplasia, in less than 1 %; this disorder must be distinguished from macronodular hyperplasia in Cushing's disease in which plasma ACTH concentrations are not suppressed. . It is essential that a careful history has excluded exogenous glucocorticoid intake. . The most common cause of hypercortisolism is ingestion of prescribed prednisolone, usually for non-endocrine disease. Blueprint in Pediatric Endocrinology 397

. Cushing's syndrome also can be caused by other oral, injected, topical, and inhaled glucocorticoid and by progestin with some intrinsic glucocorticoid activity. . Cushing's syndrome may also be caused by the use of glucocorticoid-containing creams or herbal preparations. Pseudocushing's Syndrome Hypercortisolism can occur in several disorders other than Cushing's syndrome for example, those who are physically stressed, severe obesity, especially visceral obesity or polycystic ovary syndrome and psychological conditions, especially severe major depressive disorders. Clinical Manifestations Cushing syndrome in a child is associated with distinct morbidity of growth retardation due to delayed diagnosis. Weight gain associated with failure of height gain is the classical presentation. Hirsutism, acne, premature pubic hair development may also be present. Catabolic manifestation of hypercortisolism like striae, myopathy and osteoporosis are less common in children compared to adults. Delayed puberty, oligomenorrhoea and polycystic ovaries are manifestations of gonadotropin axis involvement. . Some cases of ACTH-dependent Cushing's syndrome occur in a periodic or cyclical form, with intermittent and variable cortisol secretion, the symptoms and signs waxing and waning according to the active periods of the disease. . These patients can cause particular diagnostic difficulty, as these patients may 'cycle in' or 'cycle out' over periods of months or years; if at presentation they are eucortisolaemic, they will need regular re- evaluation to allow full investigation at the appropriate time . . Cyclicity can occur with all causes of Cushing‘s syndrome. Screening of Cushing's Syndrome Circadian Rhythm Assessment Measurement of serum cortisol at three time-points 09.00 hr and midnight (sleeping) to assess circadian rhythm. Midnight cortisol should be less than 50 nmol/l, although young children may reach their cortisol 398 Chapter 10: Adrenal Disorders

nadir earlier than midnight. Elevation of midnight sleeping serum cortisol has the greatest sensitivity of all tests for Cushing's syndrome in children. Precannulation is essential, so as not to wake the child. Urinary Free Cortisol Measurement of three consecutive 24 hour urinary free cortisol (UFC) is a non-invasive test that is widely used in the screening of Cushing's syndrome. 24-hour UFC measurements have a high sensitivity if collected correctly, values greater than threefold of normal are rare except in Cushing's syndrome. For intermediate values the specificity is somewhat lower, and thus patients with marginally elevated levels require further investigation. . The two most important factors in obtaining a valid result are: collection of a complete 24-hour specimen and a reliable reference laboratory. Overnight Dexamethasone Suppression test Dexamethasone is a synthetic glucocorticoid that is 30 times more potent than cortisol, and with an extremely long duration of action. It does not cross-react with most cortisol assays. Measurement of a 08.00 am plasma cortisol after a single dose of 1mg dexamethasone taken at midnight, and is thus considerably easier to perform. Using current specific immunoassays, most normal individuals have an 8 am serum cortisol value of less than 2 mcg / dl (55 nmol/l). Late Night Salivary Cortisol test Salivary cortisol measurement accurately reflects the plasma free cortisol concentration. Loss of the circadian rhythm of cortisol secretion by measuring night-time salivary cortisol has been studied at a number of centers as a screening test for Cushing‘s syndrome. Late-night salivary cortisol appears to be a useful and convenient additional screening test for Cushing's syndrome, particularly in the outpatient setting. The sensitivity and specificity of this test appears to be relatively consistent at different centers, ranging from 92% to 100%, and 93% to 100% respectively.

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Recommendations . Recommend at least two first-line tests should be abnormal to establish the diagnosis of Cushing's syndrome. . Late night salivary cortisol, urinary cortisol, and the low-dose dexamethasone suppression tests as first line tests. . The urinary and salivary cortisol measurements should be obtained at least twice. . The urinary cortisol excretion should be unequivocally increased (threefold above the upper limit of normal for the assay), or the diagnosis of Cushing's syndrome is uncertain and other tests should be performed. . The diagnosis of Cushing's syndrome is confirmed when two tests are unequivocally abnormal. . The patient should undergo additional evaluation if the test results are discordant or only slightly abnormal. . If test results are normal, the patient does not have Cushing's syndrome unless it is extremely mild or cyclic. . No additional evaluation unless symptoms progress or cyclic Cushing's syndrome. Low-dose Dexamethasone Suppression Test (LDDST) The two-day 2 mg test consists of administering 0.5 mg of dexamethasone every six hours for eight doses, and measurement of serum cortisol either two or six hours after the last dose. (If child weighs less than 40 kg, when to use the recommended dose of 30 µg /kg /day). Serum ortisol then measured at 0 and at 48 h, when it should be undetectable (< 1.8 mcg/dl, <50 nmol/l). These tests individually, and in combination, have a high sensitivity for Cushing's syndrome and an even higher specificity for the exclusion of this diagnosis. In normal subjects plasma concentrations fall to less than 140 nmol/l, while in Cushing's syndrome they remain above 280 nmol/l. This is a screening test, and is only of value if suppression occurs. Failure to suppress may occur in: Normal subjects due to stress, intercurrent illness, Obesity, Psychiatric disorder and estrogen treatment or pulsatile release of ortisol. Failure to suppress should prompt further evaluation as clinically indicated. 400 Chapter 10: Adrenal Disorders

High dose Dexamethasone Suppression Test (HDDST) In order to differentiate between cortisol-secreting adrenal tumors and Cushing's disease. The HDDST‘s role in the differential diagnosis of ACTH-dependent Cushing‘s syndrome is based on the same premise: that most pituitary corticotroph tumor retain some albeit reduced responsiveness to negative glucocorticoid feedback, whereas ectopic ACTH-secreting tumors like adrenal tumors typically do not. . Low-dose dexamethasone suppression test is the standard screening tests to differentiate patients with Cushing's syndrome of any cause from patients who do not have Cushing's syndrome. . High-dose dexamethasone suppression tests were used to distinguish Cushing's syndrome caused by pituitary hypersecretion of ACTH from most patients with the ectopic ACTH syndrome (Cushing's syndrome caused by non-pituitary ACTH-secreting tumors). The CRH test CRH (corticotrophin-releasing hormone) test is used for the differential diagnosis of ACTH-dependent Cushing's syndrome. Pituitary corticotrophin adenoma retains responsivity to CRH, while ectopic ACTH tumors lack CRH receptors and therefore do not respond to the agent. CRH either 1 μg / kg or 100 μg synthetic ovine (oCRH) or human sequence CRH (hCRH) is given as a bolus injection and the change in ACTH and cortisol measured. CRH test is a useful discriminator between causes of ACTH-dependent Cushing's syndrome, but which cut-off to use should be evaluated at individual centers, and caution should be exercised as there will undoubtedly be patients with the ectopic ACTH syndrome who respond outside of this cut-off. Bilateral inferior Petrosal Sampling This procedure involves placement of sampling catheters in the inferior petrosal sinuses that drain the pituitary gland. Blood for measurement of ACTH is obtained simultaneously from each sinus and a peripheral vein at two time points before and at 3-5 minutes and possibly also 10 minutes after the administration of ovine or human CRH (intravenous 1 μg / kg or 100μg respectively). A central (inferior petrosal) to peripheral plasma ACTH gradient of 2:1 or greater pre-CRH, or a gradient of 3:1 post CRH is consistent with Cushing's disease. It is Blueprint in Pediatric Endocrinology 401

also useful to lateralize microadenoma within the pituitary using the inferior petrosal sinus ACTH gradient, with a basal or post-CRH inter- sinus ratio of at least 1.4 being the criteria for lateralization used in all large studies. The accuracy of lateralization appears to be higher in children (90%), a situation where imaging is often negative. There is some discrepancy between studies as to whether CRH improves the predictive value of the test. If a reversal of lateralization is seen pre- and post-CRH, the test cannot be relied upon. Ectopic Tumors The most common site of the secretory lesion is the chest, and although small cell lung carcinomas are generally easily visualized, small bronchial carcinoid tumors that can be less than 1cm in diameter often prove more difficult. Fine-cut high-resolution CT scanning with both supine and prone images can help differentiate between tumors and vascular shadows. MRI can identify chest lesions that are not evident on CT scanning, and characteristically show a high signal on T2-weighted and short-inversion-time inversion-recovery images. The majorities of ectopic ACTH secreting tumors are of neuroendocrine origin and therefore may express somatostatin receptor subtypes. Management Transphenoidal Surgery It is widely regarded as the treatment of choice for Cushing‘s disease. The overall remission rate in various large series is in the order of 70%-75%, although higher rates of approximately 90% can be achieved with microadenoma. Of the patients achieving remission, about 25% of these will have a recurrence by 10 years. Where remission is not achieved at the first operation, re-operation may be attempted, but appears to offer prolonged remission in only around 50% of cases, and with a high risk of hypopituitarism. Adrenalectomy Adrenalectomy is the definitive treatment for all cases ACTH- independent Cushing‘s syndrome. This is either unilateral in the case of an adrenal adenoma or carcinoma or bilateral in cases of bilateral hyperplasia. In adrenal adenomas cure following surgery in skilled hands approaches 100%. Bilateral adrenalectomy is also an important 402 Chapter 10: Adrenal Disorders

therapeutic option in patients with ACTH-dependent Cushing‘s syndrome not cured by other techniques. However, the development of Nelson‘s syndrome in patients with ACTH-secreting pituitary adenoma occurs in between 8% and 38% of cases. The chance of developing Nelson‘s syndrome appears to be greater if adrenalectomy is performed at a younger age, and if a pituitary adenoma is confirmed at previous pituitary surgery. Surgery for The Ectopic ACTH Syndrome If the ectopic ACTH-secreting tumor is benign and amenable to surgical excision, such as in a lobectomy for a bronchial carcinoid tumor, the chance of cure of Cushing‘s syndrome is high. However, if significant metastatic disease is present, surgery is not curative although it may still be of benefit in selected cases. Radiotherapy Primary pituitary radiotherapy for the treatment has been shown to produce poor long-term remission rates of average of 37%. In contrast, as a second line therapy to failed pituitary surgery better results are achieved in 83%, in two and up to 5 years. The major side effect is growth hormone deficiency, occurring in 68%, with a lesser incidence of hypogonadism (40%) and hypothyroidism (16%), with only one patient developing hypocortisolaemia in the reported series. Gamma knife radio surgery is a relatively new development that has been utilized in patients with Cushing‘s disease as a second-line treatment and also in Nelson‘s syndrome. Medical Management In patients where surgery and /or radiotherapy has failed, medical management is often essential prior to (or long-term as an alternative) bilateral adrenalectomy. It may not always be possible to identify the source of ACTH in certain cases of ACTH-dependent Cushing's syndrome, and therefore medical management is desirable pending re- investigation. Finally, medical therapy is helpful as a palliative modality in patients with metastatic disease causing Cushing's syndrome. Blueprint in Pediatric Endocrinology 403

Adrenolytic Therapy These agents are primarily used as inhibitors of steroid biosynthesis in the adrenal cortex, and thus can be utilized in all cases of hypercortisolaemia regardless of the cause, often with rapid improvement in the clinical features of Cushing's syndrome. The most commonly used agents are metyrapone, ketoconazole, mitotane and in certain circumstances etomidate. Monitoring Treatment It is important to monitor all patients on medical therapy for Cushing‘s syndrome, to assess the effectiveness of treatment, and in particular to avoid adrenal insufficiency. Some use the mean of five serum cortisol measurements across the day; others favour measurement of urinary free cortisol. A mean serum cortisol between 150 and 300 nmol/l corresponds to a normal cortisol production rate, and this range should be the aim of therapy. Key Points . Cushing's disease, which is hypercortisolism caused by an ACTH- secreting pituitary adenoma, is the most common cause of Cushing's syndrome, and is responsible for 60% to 70% of cases. . The prevalence of endogenous Cushing's syndrome is greater than previously thought. . It may be difficult to distinguish patients with mild Cushing's syndrome from those with the metabolic syndrome (central obesity with insulin resistance, and hypertension). . Features more specific to Cushing's syndrome include proximal muscle weakness, increased supraclavicular fat pads, facial plethora, violaceous striae, easy bruising, and premature osteoporosis. . After exclusion of exogenous corticosteroid use, patients with suspected Cushing's syndrome should be tested for hypercortisolism with 1 of 4 high-sensitivity tests (late-night salivary cortisol; 1 mg overnight low-dose dexamethasone suppression testing, 24-hour urinary free cortisol, or 48-hour 2 mg dexamethasone suppression testing). . At least one additional test should be used to confirm hypercortisolism in patients with a positive initial screening test. 404 Chapter 10: Adrenal Disorders

. Once endogenous hypercortisolism is confirmed, plasma ACTH should be measured. . If ACTH is suppressed, diagnostic testing should focus on the adrenal glands. If ACTH is not suppressed, pituitary or ectopic disease should be sought. . In the vast majority of cases, surgical resection of the pituitary adenoma or adrenal adenoma that is causing hypercortisolism is the primary treatment of choice. Primary Hypoalosteronism (Aldosterone synthase) Deficiency Congenital hypoalosteronism is a rare inherited disorder transmitted as either an autosomal recessive or autosomal dominant trait with mixed penetrance. Isolated aldosterone deficiency results from loss of activity of aldosterone synthase encoded by CYP11B2 gene. Symptoms are present generally within the first 3 months of life, and most often after the first 5 days of life. Aldosterone synthase mediates the 3 final steps in the synthesis of aldosterone from deoxycorticosterone (11-hydroxylation, 18-hydroxylation, and 18-oxidation). Although 11-hydroxylation is required to convert deoxycorticosterone to corticosterone, this conversion can also be catalyzed by the related enzyme, CYP11B1, located in the fasciculate, which is unaffected in this disorder. For the same reason, these patients have normal cortisol biosynthesis. Infants with aldosterone synthase deficiency may have severe electrolyte abnormalities with hyponatraemia, hyperkalemia, and metabolic acidosis. However, because cortisol synthesis is unaffected, infants rarely become as ill as untreated infants with salt-losing forms of congenital adrenal hyperplasia such as 21-hydroxylase deficiency. Thus, some infants escape diagnosis. Later in infancy or in early childhood they may exhibit failure to thrive and poor growth. Adults often are asymptomatic, although they may develop electrolyte abnormalities when depleted of sodium through procedures such as bowel preparation for a barium enema. Diagnosis Infants have elevated plasma renin activity. Aldosterone levels are decreased; they may be at the lower end of the normal range but are always inappropriately low for the degree of hyperkalemia or Blueprint in Pediatric Endocrinology 405

hyperreninemia. Corticosterone levels are often elevated. It is important to distinguish aldosterone synthase deficiency from primary adrenal insufficiency in which both cortisol and aldosterone are affected (including salt-wasting forms of congenital adrenal hyperplasia) because the latter condition is usually associated with a much greater risk of shock and hyponatraemia. Pseudohypoaldosteronism may have similar electrolyte abnormalities and hyperreninemia, but aldosterone levels are high, and this condition usually does not respond to fludrocortisone treatment. Treatment consists of giving enough fludrocortisone (0.05–0.3 mg daily), sodium chloride, or both to return plasma renin levels to normal. With increasing age, salt-losing signs usually improve and drug therapy can often be discontinued. Mineralocorticoid Resistance (Pseudohypoaldosteronism type 1) Results from inability of aldosterone to exert its effect on its target tissues and was first reported by Cheek and Perry as a sporadic occurrence in 1958. This disease, usually presents in infancy with severe salt-wasting and failure to thrive, accompanied by profound urinary sodium loss, severe hyponatraemia, hyperkalemia, acidosis, hyperreninemia and paradoxically markedly elevated plasma and urinary aldosterone concentrations. Usually, renal and adrenal functions are normal. Both an autosomal dominant and a recessive form of genetic transmission were observed. All patients had renal tubular unresponsiveness to aldosterone, while some had involvement of other mineralocorticoid target-tissues, including the sweat and salivary glands, and the colonic epithelium. Autosomal recessive PHA1 presents in the neonatal period with hyponatraemia caused by multi-organ salt loss, including kidney, colon, and sweat and salivary glands. Autosomal recessive PHA1 persists into adulthood and shows no improvement over time. In contrast, autosomal dominant PHA1 is characterized by an isolated renal resistance to aldosterone, leading to renal salt loss. Particularly autosomal dominant form of PHA1 typically shows a gradual clinical improvement during childhood, allowing the cessation of sodium supplementation. Diagnosis Electrolyte profiles suggest mineralocorticoid deficiency or end- organ resistance, along with hyperkalemia, hyponatraemia and metabolic 406 Chapter 10: Adrenal Disorders

acidosis associated with profound urinary salt loss. Renal and adrenal function is normal. The diagnosis is confirmed as markedly elevated plasma aldosterone concentrations and plasma renin activity. Differential diagnosis must be made with aldosterone synthase deficiency; salt- wasting forms of congenital adrenal hyperplasia, and adrenal hypoplasia congenita, which all cause aldosterone deficiency, and are associated with hyponatraemia, hyperkalemia, hypovolemia, elevated plasma renin activity, and sometimes shock and death. Bartter syndrome II (ROMK gene mutations) can also present in the neonatal period with a similar (transient) clinical picture. Treatment Consists of salt supplementation, potassium chelating agent (sodium Resonium not calcium Resonium as the latter might cause severe constipation, the usual dose range from 0.25 – 1 gram / kg/ dose which can be given initially in severe form as frequent as 2 hourly then frequency could be weaned off gradually depending on serum potassium values). sodium bicarbonate replacement therapy as intravenous slow infusion initially in cases of emergency severe hyperkalemia and acidosis then to be shifted to oral replacement when the condition stabilizes, dose of 1-2 mmole/ kg/ dose, usually 2-3 times daily. In severe hyperkalemia salbutamol infusion or continuous neubilization should be added as adjunctive therapy. Combination of glucose and insulin infusion is also very effective measure of rapid reduction of serum potassium values, the usual dose ratio of 1 unit of insulin to each 5 grams of dextrose, for example if we need to infuse 100 cc of dextrose 10 percent, total of 10 grams of glucose, that will need 2 units of regular insulin added together and infused slowly over 15-30 minutes. Peritoneal dialysis is reserved in the severe persistent hyperkalemia. Calcium chloride infusion is used to protect the heart for arrhythmias till normalizes serum potassium levels. Administration of fludrocortisone and deoxycorticosterone is not helpful. Patients with the recessive form usually need lifelong treatment for salt wasting and hyperkalemia, whereas in the dominant form, treatment can usually be withdrawn in adulthood. Recently, carbenoxolone, an 11β-hydroxysteroid dehydrogenase inhibitor, was employed as therapy in PHA1 and an ameliorating effect Blueprint in Pediatric Endocrinology 407

was observed which was attributed to mediation by mineralocorticoid receptor. Pseudohypoaldosteronism Type II Pseudohypoaldosteronism type II also known as familial hyperkalemia and hypertension or Gordon syndrome is a volume- dependent low-renin form of hypertension characterized by persistent hyperkalemia despite a normal renal glomerular filtration rate. Hypertension is attributable to increased renal salt reabsorption and the hyperkalemia to reduced renal K+ excretion. Reduced renal H+ secretion is also commonly seen, resulting in metabolic acidosis. The features of PHA-II are chloride-dependent, because they are corrected when infusion of sodium sulfate or sodium bicarbonate is substituted for sodium chloride .these abnormalities are ameliorated by thiazide diuretics, which inhibit salt reabsorption in the distal nephron by the electroneutral Na-Cl co transporter. Clinical Presentation Pseudohypoaldosteronism-II is usually diagnosed in adults but can also be seen neonatally. Unexplained hyperkalemia is the usual presenting feature and occurs prior to the onset of hypertension. The severity of hyperkalemia varies greatly and is influenced by prior intake of diuretics and salt intake. Causes of spurious elevation of potassium should be ruled out before this diagnosis is made. In its most severe form, it is associated with muscle weakness (from hyperkalemia), short stature, and intellectual impairment. Mild hyperchloremia, metabolic acidosis, and suppressed plasma renin activity are findings variably associated with the trait. Aldosterone levels vary from low to high depending on the level of hyperkalemia. Urinary concentrating ability, acid excretion, and proximal tubular function are all normal. Treatment Thiazides reverse all biochemical abnormalities. Lower than average doses can be given if overcorrection is seen. Loop diuretics may also be used. Primary Hyperaldosteronism Hyperaldosteronism is a group of closely related conditions characterized by chronic excess aldosterone secretion. 408 Chapter 10: Adrenal Disorders

Hyperaldosteronism may be primary, or it may be secondary to an extra- adrenal cause. Primary hyperaldosteronism stems from an autonomous overproduction of aldosterone, with resultant suppression of the renin- angiotensin system and decreased plasma renin activity. Blood pressure elevation is the most common manifestation of primary hyperaldosteronism. Causes . Bilateral idiopathic hyperaldosteronism is characterized by bilateral nodular hyperplasia of the adrenal glands, is the most common underlying cause of primary hyperaldosteronism, accounting for about 60% of cases. The pathogenesis remains unclear. . Adrenocortical neoplasm, either an aldosterone-producing adenoma (the most common cause) or, rarely, an adrenocortical carcinoma. Primary hyperaldosteronism caused by solitary aldosterone- secreting adenoma, referred to as Conn's syndrome. . This syndrome occurs most frequently in adult middle life and is more common in women than in men (2:1). . Multiple adenomas may be present in an occasional patient. . Glucocorticoid-remediable hyperaldosteronism (GRA) is an uncommon cause of primary familial hyperaldosteronism. . In some families, it is caused by a chimeric gene resulting from fusion between CYP11B1 (11β-hydroxylase gene) and CYP11B2 (aldosterone synthase gene). . This leads to a sustained production of hybrid steroids in addition to both cortisol and aldosterone. The activation of aldosterone secretion is under the influence of ACTH and hence is suppressible by exogenous administration of dexamethasone. Clinical Features Few symptoms are specific, and mostly they result from hypokalemia and alkalosis by inducing renal distal tubular reabsorption of sodium, enhances secretion of potassium and hydrogen ions, causing hypernatremia, hypokalemia, and metabolic alkalosis. Patients with severe hypokalemia report fatigue, muscle weakness, cramping, Blueprint in Pediatric Endocrinology 409

headaches, and palpitations. They can also have polydipsia and polyuria from hypokalemia-induced nephrogenic diabetes insipidus. Diagnosis . Routine laboratory studies can show hypernatremia, hypokalemia, and metabolic alkalosis resulting from the action of aldosterone on the distal tubule of the kidney (enhancing sodium reabsorption and potassium and hydrogen ion excretion). Almost 20% of patients have impaired glucose tolerance resulting from the inhibitory affect of hypokalemia on insulin action and secretion; however, diabetes mellitus is rare. . Typically, renin levels are suppressed to less than 1 ng/ml/hour in patients with primary hyperaldosteronism, and levels do not stimulate above 2 ng /ml/hour with diuretics and upright posture. Because of this finding, some experts suggest that suppressed renin levels should be used as a screen for detecting primary hyperaldosteronism. . Plasma Aldosterone /plasma renin ratio "PA/PRA ratio" (obtained in the morning) of 20 or greater (with PA ≥15 ng/dl) provide a sensitivity of 100% and a specificity of 80%, indicating the need for further study. Others use a ratio greater than 30 and a PA level greater than 20 ng/dl, with a sensitivity of 90% and a specificity of 91%. Important Notices

. Plasma Aldosterone / plasma renin ratio should be calculated when the patient is not taking interfering medications. For examples, spironolactone should be stopped for 6 weeks prior to testing. . Eplerenone, is another aldosterone receptor antagonist, can also interfere with testing and should be stopped for at least 2 weeks before, diuretics, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor blockers (ARBs) can falsely elevate PRA, leading to a lower PA/PRA ratio; therefore, the presence of suppressed PRA in a patient treated with a diuretic or, especially, an ACE inhibitor or ARBs, is a strong predictor for primary hyperaldosteronism. . Because of limited specificity, a positive screening test result should be followed by a confirmatory test. 410 Chapter 10: Adrenal Disorders

. Care must be taken to ensure that potassium stores are replete and that the patient is normokalemic at the time of testing, because hypokalemia can inhibit aldosterone release and salt loading can exacerbate hypokalemia. . The most commonly used confirmatory test is a 24-hour urine aldosterone level obtained after 3 days of salt loading. A 24-hour aldosterone excretion rate of greater than 14 mcg (with a concomitant 24- h urine sodium >200 meq) is diagnostic of primary hyperaldosteronism.

Treatment In patients with primary hyperaldosteronism, the goal of treatment is to prevent the morbidity and mortality associated with hypertension and hypokalemia. The appropriate treatment depends on the cause. . A sodium-restricted diet (less than 2 g of sodium per day), maintenance of ideal body weight, and regular aerobic exercise contribute substantially to the success of pharmacological treatment. . Frequently, hypertension and hypokalemia can be controlled with potassium-sparing agent (first-step agent), such as spironolactone. . Hypokalemia is promptly corrected, but hypertension may take as long as 4-8 weeks to correct. . Potassium supplementation should not be routinely administered with spironolactone because of the potential for the development of hyperkalemia. . If hypertension persists despite titration, a second-step agent is added to the treatment. . Second-step agents include thiazides diuretics, ACE inhibitors, calcium channel antagonists, and angiotensin II blockers. . GRA is treated with physiologic doses of glucocorticoid, which correct the hypertension and hypokalemia. . Laparoscopic adrenalectomy is favored, in patients with Conn's syndrome; the blood pressure response to spironolactone preoperatively is a predictor of the blood pressure response to unilateral adrenalectomy. Blueprint in Pediatric Endocrinology 411

Pheochromocytoma Catecholamine-secreting tumor derived from chromaffin cells. Pheochromocytoma and paraganglioma are rare neoplasm in children. Tumors that arise from the adrenal medulla are termed Pheochromocytoma, and those with extra adrenal origins are called paraganglioma. Among hypertensive children, the incidence of surgically confirmed disease has ranged from 0.8 to 1.7 %. The classic triad of symptoms consists of episodic headache, sweating, and tachycardia, usually accompanied by hypertension. Symptoms caused by the mass effect of the tumor, such as abdominal pain and distension or back pain. In contrast to adults, in whom there is a high incidence of paroxysmal hypertension, most children have sustained hypertension. Malignant hypertension can occur with its associated complications (increased intracranial pressure, encephalopathy). Other signs and symptoms that occur less frequently include pallor, constipation, psychiatric disorders, blurred vision, weight loss, polyuria, polydipsia, increased erythrocyte sedimentation rate, hyperglycemia, and a dilated cardiomyopathy that may reflect the toxic effect of excess catecholamine. The clinical presentation is often different when Pheochromocytoma is associated with the multiple endocrine neoplasia type 2 (MEN2) syndromes. Symptoms are present in only approximately one-half of patients, and only one-third has hypertension. A similar finding has been observed with Pheochromocytoma associated with Von- Hippel-Lindau (VHL) disease, as 35 % of patients have no symptoms, normal blood pressure, and normal catecholamine tests. Compared to adults, children with Pheochromocytoma have a higher incidence of bilateral adrenal tumors, extra adrenal tumors, and multiple tumors. In different series, extra adrenal tumors have been described in 30 to 60 percent of children (contrasted to 10 to 15 percent of adults), and multiple tumors have been described in up to 40 percent (compared to 5 to 10 percent in adults).Catecholamine-secreting paraganglioma are co- located with chromaffin tissues (along the Para-aortic sympathetic chain, within the organs of Zuckerkandl at the origin of the inferior mesenteric artery, wall of the urinary bladder, and the sympathetic chain in the neck or mediastinum). Children and adolescents with Pheochromocytoma or paraganglioma are at risk for malignant disease. Approximately 10 % of Pheochromocytoma in adults is malignant, whereas up to 47 % of 412 Chapter 10: Adrenal Disorders

children in one series had malignant disease. Malignant Pheochromocytoma and paragangliomas are histologically and biochemically the same as benign tumors. Thus, the only clue to the presence of a malignant Pheochromocytoma is regional invasion or distant metastases, which may occur as long as 15 years after resection Laboratory Studies . Genetic testing: most patients with germ line mutations that predispose to the development of Pheochromocytoma or paraganglioma are typically not diagnosed until adulthood, onset during childhood can occur. A genetic cause should be sought in all children with Pheochromocytoma or paraganglioma. Genetic testing can be complex. Testing one family member has implications for related individuals. Genetic counseling is recommended to help families understand the implications of genetic test results, to coordinate testing of at-risk individuals, and to help families work through the psychosocial issues that may arise before, during, or after the testing process . The diagnosis in the pediatric age group is best confirmed by measurement of 24-hour fractionated urinary metanephrines and catecholamines followed by radiographic localization of the tumor. In young children in whom an accurate 24-hour urine collection is not possible, measurement of plasma fractionated metanephrines is a reasonable alternative initial test . The standard method for confirming the diagnosis of Pheochromocytoma is to measure the following urinary catecholamines and their metabolites in a 24-hour specimen: epinephrine, norepinephrine, dopamine, metanephrine, homovanillic acid (HVA) and vanillylmandelic acid (VMA). Creatinine levels should be determined for each 24-hour collection to assess the adequacy of the collection. If possible, the collection should be made while the patient is at rest, taking no medication, and without recent exposure to radiographic contrast medium. Urine should be acidified (PH < 3) and kept cold during and after the collection. The diagnostic yield is increased if the patient is symptomatic during the collection period. Important Notes . Medications and foods that are known to interfere with the assay should be avoided. Blueprint in Pediatric Endocrinology 413

. The major cause of false-positive catecholamine excretio n results is administration of exogenous catecholamines, such as levodopa, methyldopa, and labetalol, which can elevate urine concentration for as long as 2 weeks. . Certain foods can increase urinary catecholamines, including coffee, tea, bananas, chocolate, cocoa, citrus fruits, and vanilla. . The following drugs can increase catecholamine measurements: Caffeine, acetaminophen (Tylenol), Levodopa, Lithium, aminophylline, chloral hydrate, clonidine, erythromycin, insulin, methyldopa, nicotinic acid (large doses), Quinidine, tetracycline's, nitroglycerin. . Drugs that can decrease catecholamine measurements include the following: clonidine, monoamine oxidase inhibitors (MAOIs), phenothiazines, salicylates and reserpine

Other Studies . CBC count: This test is indicated when infection or abdominal pain is present. . Electrolytes, BUN, creatinine, and glucose determinations . Evaluate for lactic acidosis; renal failure secondary to hypertension, renal damage, or both; and hyperglycemia or hypoglycemia caused by the impaired insulin response. . Calcium measurement; high levels may be present because of excess of parathyroid hormone (PTH). . Urinalysis: Proteins may be found in the urine because of hypertension. . Measurement of plasma catecholamines is as follows: . Patients must be in a basal and calm state. . The measurement reflects only that single moment when the blood sample was obtained. . Basal levels of more than 2 ng /dl support the diagnosis, whereas values of less than 0.5 ng/dl make the diagnosis unlikely. . Suppression tests (phentolamine, clonidine) and stimulation tests (glucagon, histamine, and metoclopramide) have both been proposed for 414 Chapter 10: Adrenal Disorders

improving diagnostic accuracy. Stimulation tests are dangerous. Administer with extreme caution. . Measurement of plasma normetanephrine and metanephrine are useful in screening for Pheochromocytoma in patients with a familial predisposition to von Hippel-Lindau disease or MEN type 2. . Free plasma metanephrines has been found to be a highly sensitive (100%) and specific (96.7%) measure, yielding a negative predictive value of 100%. . Measurement of 24-hour urinary fractionated metanephrines using a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of Pheochromocytoma. Imaging Studies . When the diagnosis has been established, the tumor must be located to facilitate its surgical removal. Although larger tumors can usually be located easily with sonography, the smallest tumors may require CT scanning or MRI, particularly when located outside the adrenal area. . Scintigraphy with radio labeled 131I-MIBG or 123I-MIBG is indicated. MIBG scintigraphy allows whole-body exploration. Owing to its high specificity (97%), this morphological study seems to be a valuable adjunct in the detection of extra-adrenal lesions. The main limitation of MIBG scintigraphy is its slightly lower sensitivity (adrenal, 84%; extra-adrenal, 64%) than MRI (adrenal, 97%; extra-adrenal, 88%) or CT scanning (adrenal, 94%; extra-adrenal, 64%). However, despite the lower sensitivity, MIBG scanning offers the greatest specificity, and tumors seen on these images are almost certainly Pheochromocytoma. If the MIBG scanning results are positive in a child, consider a diagnosis of neuroblastoma until proven differently. . Positron emission tomography (PET) with radiopharmaceuticals provides functional imaging. It is designed to show substrate precursor uptake, cellular metabolism, or receptor binding in neoplasm with CT as a single modality; hybrid PET/CT directly correlates function and anatomy. It identifies localized Pheochromocytoma with a sensitivity of 84.6%, a specificity of 100%, and an accuracy of 92%. Arteriography and selective venous sampling are almost never indicated. However, they Blueprint in Pediatric Endocrinology 415

may be helpful in patients predisposed to multiple tumors or when clinical and biochemical evidence is consistent with Pheochromocytoma but are unsupported by other imaging modalities. . Chest radiography can be used to evaluate for pulmonary edema. Treatment . Schedule surgical removal only after successful pharmacotherapy to block the effects of catecholamine excess. Blockade of the alpha- adrenergic receptors in the preoperative phase is widely recommended, with additional beta-receptor blockade to treat cardiac dysrhythmias. . During a hypertensive crisis, immediately institute alpha-blockade with phentolamine. Nitroprusside also should be used for uncontrolled hypertension. . For further blood pressure control, initiate beta-blockade (esmolol- labetalol). A beta-blockade that is initiated without prior alpha-blockade can further exacerbate hypertension. As vasoconstriction is relieved, use vigorous fluid resuscitation to maintain a normal blood pressure. . Ventricular tachyarrhythmia can be treated with lidocaine and amiodarone. . Chemotherapy and radiotherapy have been of questionable value in patients with unrespectable disease. Unrespectable disease may be rendered resectable by intensive chemotherapy. Chemotherapy currently has a response rate of approximately 50%. . Sunitinib appears to be an active agent in the treatment of malignant Pheochromocytoma. Sunitinib inhibits cellular signaling by targeting multiple receptor tyrosine kinases, such as platelet-derived growth factor receptors, and vascular endothelial growth factor receptors, which play a role in both tumor angiogenesis and tumor cell proliferation. . Patients with germ line mutation and no evidence of active illness should have continued follow-up for Pheochromocytoma. . Preoperative blockade of alpha-1 receptors has been used to reduce the risk of hypertensive episodes. Drugs such as urapidil have shown a significant reduction in hypertensive peaks. 416 Chapter 10: Adrenal Disorders

. Tran abdominal surgery has been the traditional approach; it allows early ligation of the adrenal vein to minimize systemic catecholamine release during manipulation. This approach also facilitates exploration of the sympathetic chain for multifocality. . Other options include a subcostal or posterior extra peritoneal approach that offers rapid recovery and avoids the risk of transperitoneal surgery (adhesions, bowel obstruction). Alternatively, a laparoscopic adrenalectomy can be considered; tumors as large as 11 cm have been successfully removed. The contraindications to laparoscopy include evidence of soft-tissue or vascular extra-adrenal extension. Bilateral tumors develop in children with multiple endocrine neoplasia type 2 and Pheochromocytoma, and bilateral adrenalectomy has been recommended at presentation. . Careful and intensive monitoring of the patient's status throughout the perioperative period is imperative. . Hypotension that develops after tumor removal reflects reversal of the volume-contracted state and should respond to judicious replacement of fluids. . Some patients may develop pulmonary edema, possibly as a result of impaired myocardial function and the inability to tolerate intravenous fluids. . When the tumor is removed, the blood pressure usually falls to approximately 90/60 mm Hg. Lack of a fall in pressure at the time of tumor removal indicates the presence of additional tumor tissue. . When bilateral adrenal tumors are found and both adrenals are removed, adrenocortical lifelong steroid replacement is required. Significant morbidity is associated with bilateral adrenalectomy. Because of these risks, some clinicians have recommended adrenal-sparing surgery in patients who have bilateral tumors or who are at particular risk for a metachronous contra lateral tumor.

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References and Further Reading 1. Korosi A, Baram TZ. The central corticotropin releasing factor system during development and adulthood. Eur J Pharmacol. 2008; 583(2-3):204-214. 2. Yudt MR, Cidlowski JA. The glucocorticoid receptor: coding a diversity of proteins and responses through a single gene. Mol Endocrinol. 2002;16(8):1719- 1726. 3. Bolt RJ, van Weissenbruch MM, Popp-snijders C, Sweep FGJ, Lafeber HN, Delemarre-van de Waal HA.Maturity of the adrenal cortex in very preterm infants is related to gestational age. Pediatr Res. 2002; 52:405-410. 4. Rosenfield RL. Identifying children at risk for polycystic ovary syndrome. J Clin Endocrinol Metab. 2007; 92(3):787- 796. 5. Catania A. The melanocortin system in leukocyte biology. J Leukoc Biol. 2007; 81(2):383-392. Rask E, Olsson T, Sِderberg, et al. Tissue-specific dysregulation of cortisol .6 metabolism in human obesity. J Clin Endocrinol Metab. 2003; 86:1418-1421. 7. Cooper MS, Stewart PM. Corticosteroid insufficiency in acutely ill patients. N Engl J Med. 2003; 348(8):727-734. 8. Migeon CJ, Tyler FH, Mahoney JP, et al. The diurnal variation of plasma levels and urinary excretion of 17-hydroxycorticosteroids in normal subjects, night workers, and blind subjects. J Clin Endocrinol Metab. 1956; 16:622. 9. Papanicolaou DA, Mullen N, Kyrou I, Nieman LK. Nighttime salivary cortisol: a useful test for the diagnosis of Cushing‘s syndrome. J Clin Endocrinol Metab. 2002; 87:4515-4521. 10. 10.Saxena A, Hanukoglu I, Saxena D, Thompson RJ, Gardiner RM, Hanukoglu A. Novel mutations responsible for autosomal recessive multisystem pseudohypoaldosteronism and sequence variants in epithelial sodium channel-, a-, b-, and g-subunit genes. J Clin Endocrinol Metab. 2002; 87(7):3344-3350. 11. Kino C. Glucocorticoid and mineralocorticoid resistance/ hypersensitivity syndromes. J Endocrinol. 2001; 169(3):437-445. 12. Long DN, Wisniewski AB, Migeon CJ. Gender role across development in adult women with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. J Pediatr Endocrinol Metab. 2004; 17:1367-1373. 13. Batista DL, Riar J, Keil M, Stratakis CA. Diagnostic tests for children who are referred for the investigation of Cushing Syndrome. Pediatrics 2007; 120:e575- e586. 14. Yaneva M,Mosnier-Pudar H, Dugué M-A, Grabar S, Fulla Y, Bertagna X. Midnight salivary cortisol for the initial diagnosis of Cushing‘s syndrome of various causes. J Clin Endocrinol Metab. 2004;89:3345-3351 418 Chapter 10: Adrenal Disorders

15. Scheen AJ, Lefèbvre PJ. Reactive hypoglycaemia, a mysterious, insidious but non-dangerous critical phenomenon. Rev Med Liege [French]. 2004; 59(4):237-242. 16. Palladino AA, Bennett MJ, Stanley CA. Hyperinsulinism in infancy and childhood: when an insulin level is not always enough. Clin Chem. 2008; 54(2):256-263. 17. Cornblath M, Hawdon JM, Williams AF, et al. Controversies regarding definition of neonatal hypoglycemia: suggested operational thresholds. Pediatrics. 2000; 105(5):1141-1145. De Leَn DD, Stanley CA. Mechanisms of disease: advances in diagnosis and .18 treatment of hyperinsulinism in neonates. Nat Clin Pract Endocrinol Metab. 2007; 3(1):57-68. 19. Freeze HH. Congenital disorders of glycosylation: CDG-I, CDG-II, and beyond. Curr Mol Med. 2007;7(4):389-396. Lloyd RV, Erickson LA, Nascimento AG, Klِppel G. Neoplasms causing .20 nonhyperinsulinemic hypoglycemia. Endocr Pathol. 1999; 10(4):291-297. 21. Mehta A, Dattani MT. Developmental disorders of the hypothalamus and pituitary gland associated with congenital hypopituitarism. Best Pract Res Clin Endocrinol Metab. 2008; 22(1):191-206.

Chapter 11 Pediatric Obesity and Hyperlipidemia

. Introduction . Definition of pediatric obesity . Pathophysiology . Etiology pediatric obesity . Evaluation of child with obesity . Indices of body fat . BMI . Waist circumference . Skin fold thickness . Definition of pediatric metabolic syndrome . Approach to Obese Children and Adolescents o Laboratory evaluations o Radiological studies o Councelling . Lifestyle modification for Overweight and Obese children and adolescents . Treatment of associated co-morbidities . Dyslipidemia in children o Causes . Characteristics of Some Primary Genetic Dyslipidemia . Familial hypercholesterolemia . Familial defective APOB-100 . Familial combined hyperlipidemia . Familial hypertriglyceridemia . Lipoprotein lipase deficiency . Familial dysbetalipoproteinemia . Small, dense LDL syndromes . Characteristics of secondary Dyslipidemia o Treatment . Hypercholesterolemia . Hypertriglyceridemia . Hyperchylomicronemia

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Introduction

Obesity has become one of the most important public health problems worldwide. The body mass index (BMI) is the accepted standard measure of overweight and obesity for children two years of age and older. The BMI provides a guideline for weight in relation to height; it is equal to the body weight (in kilograms) divided by the height (in square meters).

Fig. (11-1): Obesity due to over eating

Definition of Pediatric Obesity . Underweight: BMI < 5th percentile for age and sex. . Normal weight: BMI between the 5th and 85th percentile for age and sex. . Overweight: BMI between the 85th and 95th percentile for age and sex. . Obese: BMI ≥ 95th percentile for age and sex. . Severe obesity: BMI ≥120 percent of the 95th percentile values or BMI ≥ 35 (corresponds to 99th percentile or BMI z-score ≥2.33).

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Children with severe obesity have significantly more cardiovascular risk factors and a greater risk for having obesity in adulthood. The prevalence of childhood overweight and obesity is also increasing in most developing and developed countries worldwide. Key Points . Behavioral and environmental factors are primarily responsible for the dramatic increase in obesity in the past 2 decades, although genes play an important role in regulation of body weight. . Calculating BMI is the most widely accepted method of screening for obesity in children. . Abnormal BMI cut-offs in children are determined by age- and gender-specific percentiles. . The dramatic increase in childhood obesity has led to a marked increase in the diagnosis of impaired glucose tolerance and type 2 diabetes mellitus in children. . Preventing excessive weight gain in children is of paramount importance in confronting the obesity epidemic, as obesity is difficult to treat at all ages, and obese children tend to become obese adults. . The mainstay of treatment is lifestyle modification to improve diet and increase physical activity. Pharmacotherapy and bariatric surgery may be considered as an adjunct to lifestyle modification in the morbidly obese adolescent. The influence of maternal nutrition and intrauterine environment are reflected primarily in the growth parameters at the time of birth, whereas genetic factors have a later influence. Thus, the weight percentile of some children whose birth weight percentile is less than what would be expected based upon family growth patterns may increase over time. It is difficult to predict which overweight children will become obese adults. The likelihood of persistence of childhood obesity into adulthood is related to age, parental obesity, and severity of obesity. Girls are more prone than boys to develop persistent obesity during adolescence. This is related to changes in body composition that occur at puberty, when body fat decreases in boys and increases in girls. Obesity in adolescent boys is Blueprint in Pediatric Endocrinology 423

more likely to be persistent, and the risk of persistent obesity was close to that of girls. Pathophysiology Several physiological systems control how the body regulates its weight. The arcuate nucleus, located in the hypothalamus, serves as the master centre of weight regulation by integrating hormonal signals which direct the body to adjust its food intake and energy expenditure. The arcuate nucleus contains two major types of neurons with opposing actions. Activation of the peptide neurotransmitters neuropeptide Y (NPY) and agouti-related peptide (AgRP) leads to stimulation of appetite and decrease in metabolism. In contrast, activation of pro- opiomelanocortin (POMC) /cocaine and amphetamine-regulated transcript neurons causes release of melanocyte-stimulating hormone, which inhibits eating. Short-term feeding has been linked to two peptide hormones produced in the digestive tract, ghrelin and peptide YY, which control how much and how often we eat on a given day. Ghrelin is a potent appetite stimulator which is produced in the stomach and activates the NPY/AgRP neurons. Increased ghrelin levels are associated with meal initiation. Peptide YY may play an important role in satiety, as it activates the POMC neurons while inhibiting the NPY/AgRP neurons. Longer-term weight regulation, over months to years, is linked to leptin and insulin. When fat stores and leptin levels decrease, NPY/AgRP neurons are activated and POMC neurons are inhibited, thereby stimulating weight gain. The opposite occurs with increased fat mass and increased leptin levels. Etiology Pedatric Obesity Environmental Factors Almost all obesity in children is strongly influenced by environmental factors, caused by either a sedentary lifestyle or a caloric intake that is greater than needs. The contributions of specific environmental influences are the subject of considerable discussion and research. Increasing trends in glycaemic index of foods, sugar-containing beverages, portion sizes for prepared foods, fast food service, diminishing family presence at meals, decreasing structured physical activity, increasing use of computer-oriented play activity, and elements 424 Chapter 11:Pediatric Obesity and Hyperlipidemia

of the built environment (e.g. availability of sidewalks and playgrounds) have all been considered as causal influences on the rise in obesity. . Number of well-designed studies has shown associations between intake of sugar-containing beverages or low physical activity and obesity or metabolic abnormalities . Television viewing is perhaps the best established environmental influence on the development of obesity during childhood. The amount of time spent in watching television is directly related to the prevalence of obesity in children and adolescents. . The use of electronic games also has been associated with obesity during childhood. A few video games have been specifically designed to provide nutritional education and encourage healthy habits. Others require interactive physical activity by the player. Activity-enhancing games generally cause a small increase in energy expenditure during playing time. . Cross-sectional studies suggest an association between shortened sleep duration and obesity or insulin resistance, after adjustment for a number of potential environmental confounders; the effects are more marked in children at the upper end of the weight range. The mechanism for the association has not been established, but may include alterations in serum leptin and ghrelin levels, both of which have been implicated in the regulation of appetite, or perhaps a longer opportunity to ingest food. . A number of drugs can cause weight gain, including psychoactive drugs (particularly olanzapine and risperidone), antiepileptic drugs, and glucocorticoid. Brief courses of glucocorticoid (e.g., several days for an exacerbation of asthma) are unlikely to have long-term effects on body weight unless they are prescribed frequently. Weight gain and hyperlipidemia induced by olanzapine may be particularly severe in adolescents as compared to adults. . Preliminary evidence suggests the possibility that obesity can be triggered or exacerbated by exposure to a virus. Adenovirus 36 increases body fat in several animal models. Human studies, including a small study in twins, have shown an association between adenovirus 36 antibodies and obesity. Possible explanations for the observations in humans include a true causal association, vulnerability to adenovirus Blueprint in Pediatric Endocrinology 425

infection or persistence among individuals with obesity or the presence of unmeasured confounders. . Genetic factors play a permissive role and interact with environmental factors to produce obesity. Studies suggest that heritable factors are responsible for 30 to 50 percent of the variation in adiposity, but most of the genetic polymorphisms responsible have not yet been isolated. Thus, genetic contributions to common obesity likely exist, but most of the molecular mechanisms for these factors have yet to be determined. . A variety of specific syndromes and single-gene defects which are linked to obesity in childhood has been identified. These are rare causes of obesity, accounting for less than one percent of childhood obesity in tertiary care centers In addition to being overweight, children with genetic syndromes associated with obesity typically have characteristic findings on physical examination. These include dysmorphic features, short stature, developmental delay or intellectual disability (mental retardation), retinal changes, or deafness. For most of the syndromes, including Prader-Willi syndrome, the genetic cause has been sufficiently isolated to permit specific testing, but the exact mechanism through which they cause obesity is not understood or is attributable to multiple genes. Other disorders are attributable to a mutation in a single gene involved in regulation of body weight, although the mutations also may have effects on pigmentation (POMC) and the reproductive system. Several of these affect the melanocortin pathway in the central nervous system. The most common single gene defect currently identified in populations with severe obesity are mutations in the melanocortin 4 receptor, but this is still rare, accounting for only about four to six percent of severe obesity. . Endocrine causes of obesity are identified in less than 1 percent of children and adolescents with obesity. The disorders include hypothyroidism, cortisol excess (e.g., the use of corticosteroid medication, Cushing syndrome), growth hormone deficiency, and acquired hypothalamic lesions (e.g., infection, vascular malformation, neoplasm, trauma). Most children with these problems have short stature and/or hypogonadism 426 Chapter 11:Pediatric Obesity and Hyperlipidemia

. Metabolic programming as there is an increasing evidence that environmental and nutritional influences during critical periods in development can have permanent effects on an individual's predisposition to obesity and metabolic disease. The precise mediators and mechanisms for these effects have not been established, but are the subject of ongoing investigations. . Maternal nutrition or endocrine profile during gestation is probably an important determinant of metabolic programming, as illustrated by the following studies: Individuals born small for gestational age (SGA) or large for gestational age (LGA) have higher rates of insulin resistance during childhood, even after controlling for obesity status. Similarly, many population-based studies confirm an association between birth weight (reflecting fetal nutrition) and later diabetes, heart disease, insulin resistance, and obesity. Infancy and early childhood are probably also critical periods for metabolic programming. Studies in a variety of populations have shown consistent associations between rates of weight gain during infancy or early childhood and subsequent obesity or metabolic syndrome during early childhood, adolescence or adulthood. Similarly, a preponderance of evidence suggests that breastfeeding has a modest protective effect on the development of obesity. Evaluation of Child with Obesity History The history should include the age of onset of overweight and information about the child's eating and exercise habits. The age of onset is helpful in distinguishing overfeeding from genetic causes of overweight since syndromic overweight often has onset before two years of age. The dietary history should include; identification of foods high in calories and low in nutritional value that can be reduced, eliminated, or replaced (juice, soft drinks), assessment of eating patterns (timing, content, and location of meals and snacks); child or adolescent who feels unable to control consumption of large amounts of food may have an eating disorder, Evaluation of time spent in play and assessment of screen-time (television, videotapes and DVDs, and video games). The review of systems should probe for evidence of co morbidities or underlying etiologies. The risk of co morbidities of obesity is strongly influenced by the family history of such morbidities, whether or not the Blueprint in Pediatric Endocrinology 427

affected family member is overweight. Obesity in one or both parents is an important predictor for whether a child's obesity will persist into adulthood. Thus, the family history should include information about obesity in first-degree relatives (parents and siblings). It also should include information about common co morbidities of obesity, such as cardiovascular disease, hypertension, diabetes, liver or gall bladder disease, and respiratory insufficiency in first- and second-degree relatives (grandparents, uncles, aunts, half-siblings, nephews and nieces). Physical Examination Children who are overweight or obese have a higher prevalence of hypertension; thus, blood pressure should be measured. Acanthosis nigricans is often seen in obese children and is associated with insulin resistance. Acne and/or hirsutism are associated with polycystic ovary syndrome. Definitions of Pediatric Metabolic Syndrome (IDF Criteria) . Central obesity . Waist circumference > 90th %ile for age, gender, and ethnicity or o Male adolescent  94 cm o Female adolescent  80 cm Plus any Two of The Following . Raised triglycerides  150 mg/dL . Reduced HDL cholesterol < 40 mg/dL (< 50 mg/dL in females >16 years of age). . Raised systolic blood pressure  130 mm Hg or diastolic > 85 mm Hg. . Elevated fasting plasma glucose Fasting plasma glucose ≥ 100 mg / dL or previously diagnosed type 2 diabetes. BMI The most widely accepted measure of body fat is calculation of BMI (weight in kilograms divided by height in square meters). Accurate measurements of both height and weight are therefore very important. 428 Chapter 11:Pediatric Obesity and Hyperlipidemia

Abnormal BMI cut-offs in children are determined by age and gender- specific percentiles based on growth charts. For children < 2 years of age, BMI percentiles are not available; thus, obesity may be defined as a weight ≥ 95th percentile for height.Although BMI is an indirect measure of body fat, it has been found to correlate with adiposity. It, however, does not distinguish between subcutaneous and visceral fat (which has been shown to be associated with cardiovascular and metabolic risk factors). Children that are very muscular may have a BMI in the abnormal range despite having normal to low adiposity. Waist Circumference Waist circumference or waist-hip ratio can be used as an indirect measure of visceral adiposity (which has been shown to be associated with cardiovascular and metabolic risk factors). Measurement of waist circumference is non-invasive and may be helpful in addition to BMI to identify overweight children at a higher metabolic risk. Waist circumference percentiles have been developed for children aged 2 to 18 year of age. However, the cut-off values which would indicate risk above that of BMI measurement are not available Skin Fold Thickness . Skin fold thickness provides information about body fat and the risk of medical complications. . It is difficult to perform accurately, and reference data in children are not readily available. . It is not recommended in the general clinical setting. Important aspects of assessment of general appearance include assessment for dysmorphic features, which may suggest a genetic syndrome, features like, microcephaly is a feature of Cohen syndrome, and Blurred disc margins may indicate pseudo tumor cerebri. Pigmentation in the peripheral retina may indicate retinitis pigments, which occurs in Bardet-Biedl syndrome. Assessment of the fat distribution helps to distinguish the etiology of obesity. The excess fat in obesity from overeating or overfeeding usually is distributed in the trunk and periphery. In contrast, the "buffalo type" distribution of body fat (concentrated in the interscapular area, face, neck, and trunk) is Blueprint in Pediatric Endocrinology 429

suggestive of endocrine causes of obesity, such as Cushing syndrome and hypothyroidism. Abdominal obesity (also called central, visceral, android, or male-type obesity) is associated with certain co morbidities, including the metabolic syndrome, polycystic ovary syndrome, and insulin resistance. Measurement of the waist circumference, in conjunction with calculation of the BMI, may help to identify patients at risk for these co morbidities. A careful blood pressure should be obtained with a proper sized cuff. Hypertension increases the long-term cardiovascular risk in overweight or obese children. In addition, hypertension may be a sign of Cushing syndrome. Hypertension is defined as a blood pressure greater than the 95th percentile for gender, age and height on three separate occasions. Age- and height-specific blood pressure percentiles also may be determined using calculators for boys or for girls. Assessment of stature and height velocity is useful in distinguishing exogenous obesity from obesity that is secondary to genetic or endocrine abnormalities. Exogenous obesity drives linear height, so most obese children are tall for their age. By contrast, most endocrine and genetic causes of obesity are associated with short stature. Growth velocity may be slowed in children with endocrine causes of obesity, and children with Prader-Willi syndrome are often short for their genetic potential and/or fail to have a pubertal growth spurt. Examination of the skin and hair is particularly useful in evaluating signs of endocrine etiologies or complications: Dry, coarse, or brittle hair may be present in hypothyroidism. Striae and ecchymoses are manifestations of Cushing syndrome; however, striae may also just be the result of rapid accumulation of subcutaneous fat. Acanthosis nigricans may signify type 2 diabetes or insulin resistance. Hirsutism may be present in polycystic ovarian syndrome (PCOS) and Cushing syndrome. Hepatomegaly may be a clue to nonalcoholic fatty liver disease. The musculoskeletal examination may provide evidence of underlying etiology or co morbidity of childhood overweight: nonpitting edema may indicate hypothyroidism. Postaxial polydactyly (extra digit next to the fifth digit) may be present in Bardet- Biedl syndrome, and small hands and feet may be present in Prader-Willi syndrome. The genitourinary examination and evaluation of pubertal stage may provide evidence of genetic or endocrine causes of obesity. 430 Chapter 11:Pediatric Obesity and Hyperlipidemia

Undescended testicles, small penis, and scrotal hypoplasia may indicate Prader-Willi syndrome. Micro-orchidism may suggest Prader-Willi or Bardet-Biedl syndrome. Delayed puberty may occur in Cushing syndrome, Prader-Willi syndrome, and Bardet-Biedl syndrome. Approach to Obese Children & Adolescents . Taking an extended medical history including; early onset of diabetes, familial lipid disorders, parental metabolic syndrome, pain syndromes (headache, abdominal pain, painful exercise), indications of sleep apnea, drug history, eating behavior, psychiatric history, and excessive media consumption. . Exclusion of endocrine dysfunction (hypothyroidism, hypercortisolism, hypothalamic dysfunction) . Assessment of the metabolic profile (glucose-metabolism, lipid- metabolism, liver and kidney function and pubertal hormones). A glucose-tolerance-test is obligatory in extreme obesity. . Genetic analysis for monogenetic causes of obesity (MC4-recepter; POMC-receptor); and Prader-Willi-Syndrome. . Evaluation for cardiovascular risk (blood pressure, extended lipid profile, and echocardiography) . Polysomnography (sleep laboratory) Laboratory Evaluation . A fasting glucose of 100 to 125 mg/dl is considered to be prediabetic, and a level of ≥126 mg per dl (7.0 mmole/L) is consistent with the diagnosis of diabetes. Children with an elevated fasting glucose should have a confirmatory oral glucose tolerance test (OGTT) or be referred to an endocrinologist for further evaluation. . Measurement of hemoglobin A1C is a useful marker of chronic blood glucose concentration. Patients with hemoglobin A1C 5.7-6.4 percent are considered prediabetic, and those with hemoglobin A1C > 6.5 percent probably have diabetes. . Fasting serum insulin of >17 µU/ml (122 pmol/l) is considered to be elevated and may be associated with insulin resistance. It should be noted that fasting insulin levels are an unreliable measure of insulin Blueprint in Pediatric Endocrinology 431

sensitivity, because they are poorly correlated with whole body insulin sensitivity as measured by the euglycemic hyperinsulinemic clamp. . For patients with elevated fasting insulin levels we explain that there is a significant likelihood that type 2 diabetes mellitus will eventually develop if weight loss is not achieved. . Obese children with hyperlipidemia should be monitored and perhaps treated, since hyperlipidemia increases the risk of atherosclerosis as the obese child grows older. Fasting total cholesterol of >200 mg/dl (5.18 mmole/L) or a LDL cholesterol of >130 mg/dl (3.38 mmole/l) is consistent with hyperlipidemia. Fasting serum triglycerides of >150 mg/dl (1.70 mmole/l) in adolescents with obesity are considered to be elevated and an early sign of the "metabolic syndrome". . Liver function tests should be obtained because nonalcoholic fatty liver disease (NAFLD) is typically asymptomatic. Obese children with an elevation of ALT greater than two times the norm that persists for greater than three months should be evaluated for the presence of NAFLD and other chronic liver diseases (viral hepatitis, autoimmune hepatitis, Wilson disease and alpha-1 antitrypsin deficiency). . Screening for vitamin D deficiency is undertaken; levels are measured as serum vitamin D. . Additional testing may be necessary if there are findings consistent with hypothyroidism, PCOS, Cushing syndrome, and sleep apnea. . Endocrine causes of obesity are unlikely if the growth velocity is normal during childhood or early adolescence. Radiological Studies . Plain radiographs of the lower extremities should be obtained if there are clinical findings consistent with slipped capital femoral epiphysis (hip or knee pain, limited range of motion, abnormal gait) or Blount disease (bowed tibia). . Abdominal ultrasonography may be indicated in children with findings consistent with gallstones (abdominal pain, abnormal transaminases). Abdominal ultrasonography also may be used to confirm the presence of fatty liver. 432 Chapter 11:Pediatric Obesity and Hyperlipidemia

. Pelvic ultrasound to look for radiological signs of PCOS in obese female adolescents. . DXA scan is a safe method for assessing total body fat. However, its use is limited by the expense of the method, and the inability to distinguish between subcutaneous and visceral fat. It is used mainly in the research setting. . CT scan or MRI of the abdomen can be used to accurately measure visceral fat. However, these methods are costly and should only be done in the research setting Other Complications . Pseudotumor cerebri (should also be referred to a pediatric neurologist). . Sleep apnea (should also be referred to a pediatric pulmonologist). . Obesity - hypoventilation syndrome (should also be referred to a pediatric pulmonologist). . Slipped capital femoral epiphysis or Blount disease (should also be referred to a pediatric orthopedic). Counseling Therapy to modify behavior is likely beneficial along with dietary changes and increased exercise If there is no improvement in BMI after 6 months, or parental obesity is present, more intense counseling is provided for structured weight management. Lifestyle Modification Overweight Children (BMI ≥85th to 94th percentile) Lifestyle modification is the initial and main treatment for all children with a BMI ≥85th percentile. Children should be encouraged to eliminate sugar-sweetened beverages, decrease portion sizes, and limit both energy-dense and fast foods. Diets rich in fruits and vegetables should be suggested and healthy food choices should be offered in the school. Family meals should be encouraged and family involvement is imperative. If possible, unhealthy foods should be removed from the home. Many diets exist, but there is no evidence to recommend one diet Blueprint in Pediatric Endocrinology 433

over another for children. Children should be encouraged to get at least 60 minutes of physical activity per day. The activity should be age appropriate and fun for the child to encourage compliance. Family involvement in promoting physical activity is also encouraged. Exercise alone is not as effective as when combined with dietary modifications. Television viewing and other screen time (e.g., computer and video games, internet) should be limited to <2 hours daily, as this has been associated with risk of obesity. Obese Children (BMI ≥ 95th to 99th percentile) All children and their families should be counseled on healthy lifestyle modifications. If there is no improvement in BMI in 6 months, or parental obesity is present, more intense counseling is provided for structured weight management, and referral for comprehensive multidisciplinary intervention should be considered. Age 2 to 11 years: The goal of treatment is weight maintenance or gradual weight loss not to exceed 0.5 kg per month. Age 12 to 18 years: The goal of treatment is weight loss not to exceed 19 kg per week. Children with an inadequate weight response should be referred for tertiary care interventions, which may include medications. Two medications have been approved in some countries for use in children orlistat, which inhibits fat absorption through the inhibition of enteric lipase and is approved in some countries for children ≥12 years of age; and sibutramine "serotonin reuptake inhibitor" which acts as an anorectic and is approved in some countries for obese patients' ≥16 years of age. While sibutramine was suspended marketing in January 2010 due to safety concerns. . Although not approved for the treatment of obesity, Metformin has been shown to cause weight loss (average BMI change - 0.5 kg/m2) with relatively few adverse effects) Bariatric surgery in extremely obese adolescents is requested more intensively over the last years. Weight reduction and short term positive metabolic effects are demonstrated in relatively small clinical studies for various surgical procedures (mainly gastric banding). Because only long term aftercare and follow up can provide the evidence for risks, harm and benefit of this invasive treatment procedure, all extremely obese 434 Chapter 11:Pediatric Obesity and Hyperlipidemia

adolescents who underwent bariatric surgery should be included into clinical trials. Treatment of Associated Morbidities . Attention to cholesterol and triglycerides and initiation of statin therapy and low fat diets when recommended by the current guidelines. . Insulin resistance and impaired glucose regulation: Weight reduction normalizes impaired glucose tolerance and preserves insulin function. The use of Metformin is recommended in some centers. . Non-Alcoholic fatty liver disease (NAFLD): Special attention must be made to prevent NAFLD from progressing to steatoheoatitis, which is diagnosed via liver biopsy. Treatment is via weight reduction, low fat and low sugar diet, vitamin E supplementation, and Metformin. . Hypertension treatment according to the American Heart Association guidelines. . Pubertal disorders: Oligo- and dysmenorrheal are present in nearly 50% of extremely obese girls, partially in combination with hyperandrogenaemia, insulin resistance and polycystic ovaries (PCOS). Metformin as well as anti-androgen medications and oral contraceptives are effective therapeutic modalities. Important Notices . Children with an inadequate weight response should be referred for tertiary care interventions, which may include medications or bariatric surgery. . Surgery should only be considered in girls ≥13 years of age, or boys ≥15 years of age with BMI of ≥40 with other health risks, or BMI >50, who have been involved in a behavioral treatment program for ≥6 months. . The surgical approaches used most often are laparoscopic gastric banding and the Roux-en-Y gastric bypass. Data on outcomes in the adolescent population are limited. . Surgery reduces caloric intake by either restrictive or malabsorptive mechanisms. Patients must be committed to a lifetime of altered eating habits following surgery. Blueprint in Pediatric Endocrinology 435

. There are extensive perioperative risks and post-procedural nutritional risks. . Surgery should only be performed by an experienced surgeon who works with a team capable of following the patient for long-term metabolic or psychosocial issues. Dyslipidemia in Children Evidence has accumulated showing that some risk factors leading to coronary artery disease (CAD) in adulthood are operative during the first two decades of life. Children and adolescents with high cholesterol levels are more likely than the general population to have high levels when they become adults. In the general population, total cholesterol levels are generally 40 mg/dl higher in adults than in childhood. Data clearly show that cholesterol and other cardiovascular risk factors often persist from childhood to adulthood. Most authors and consensus reports identify the following risk factors in childhood as: dyslipidemia, hypertension, obesity, sedentary lifestyle, and smoking in adolescents. Others, such as hyperhomocystinemia, are currently under study and may join the list in the near future. Autopsy studies demonstrate that aortic and coronary atherosclerosis is commonly seen before age 20 years. High serum total cholesterol, LDL cholesterol, very-low-density lipoprotein (VLDL) cholesterol levels, and low HDL cholesterol levels are correlated with the extent of early atherosclerotic lesions in adolescents and young adults. Antemortum total and LDL cholesterol levels, blood pressure, BMI, and fasting insulin were all positively correlated with aortic and coronary artery fatty streaks and plaques. Increased BMI and blood pressure and decreased HDL correlated with the early development of coronary calcification, considered a marker for atherosclerosis. Identified risk factors contributing to the early onset of CHD in children / adolescents include; elevated LDL, family history of premature coronary heart disease, CVD, or peripheral vascular disease, smoking, hypertension, HDL < 35 mg/dl, obesity ( ≥ 95th percentile weight for height), physical inactivity and diabetes. Recommendations currently made for children in general that is, lipid levels should be measured initially in children (more than 2 years of 436 Chapter 11:Pediatric Obesity and Hyperlipidemia

age) only in the presence of a positive family history (parental total cholesterol level ≥ 240 mg/dl and /or cardiovascular event in a parent before age 55 years). The preferred test is the fasting lipid profile. Dyslipidemia is defined by laboratory testing and statistically determined criteria. An elevated LDL-C level is the most common clinically significant marker of dyslipidemia in children. Causes . Primary genetic diseases include, Familial hypercholesterolemia, Familial defective APOB-100, autosomal recessive hypercholesterolemia, Familial combined hyperlipidemia, Familial hypertriglyceridemia, Lipoprotein lipase deficiency, Small, dense LDL syndromes, Abnormalities of APOA-1 with diminished HDL and elevated lipoprotein (a). Secondary dyslipidemia: Metabolic syndrome, obesity, diabetes mellitus types 1 and 2, nephrotic syndrome, chronic renal disease, hypothyroidism, and drug therapies. . The majority of children with dyslipidemia will have idiopathic dyslipidemia (polygenic, risk factor–associated, or Multifactorial), whereas a minority will have monogenic. The more common genetic dyslipidemia include familial hypercholesterolemia (FH), familial combined hyperlipidemia (FCH), familial defective apoprotein-B, and familial hypertriglyceridemia. Characteristics of Primary Genetic Dyslipidemia Familial Hypercholesterolemia . It is notable for an early clinical presentation of atherosclerotic cardiovascular disease and occurs with a prevalence of about 1/500 people across most populations. . It is inherited in an autosomal-dominant pattern, mapping to chromosome 19 (p13.2–p13.1). Hundreds of different mutations have been noted, including point mutations, deletions, and gene rearrangements, leading to a variety of abnormalities. . The primary defect is in the LDL receptor, either through a reduced number of receptors or through reduced receptor activity. With this condition, there is a reduction in hepatic clearance of intermediate density lipoprotein (IDL) and LDL, as well as hepatic overproduction of LDL. Blueprint in Pediatric Endocrinology 437

. Naturally, there is a much more severe presentation in the homozygous state, in which both alleles of the LDL receptor gene are abnormal, usually in different ways. In this extremely rare condition of homozygous dysfunction of the LDL receptor (occurring at a frequency of approximately 1/1,000,000 individuals), cholesterol levels > 2000 mg/dl may be seen, as may cardiac events in the first decade of life. . Typically, heterozygous disease present with myocardial infarction or other cardiac events in the fourth decade. Other clinical findings include a significant fraction of patients with tendinous exanthema or arcus cornea, although these signs tend to be seen in adulthood. . Among adolescents, up to 10% may have tendinous exanthemas. Laboratory studies show severely elevated total cholesterol (250–450 mg/dl) and LDLC (180–300 mg/dl). . It should be noted that these extremely high values may fall by 20% or more during adolescence before rising again, sometimes obscuring the diagnosis. There are no consistent changes in HDL-C, and triglycerides and apolipoprotein B (APOB) are normal. . Treatment is directed at agents that decrease the hepatocellular concentration of saturated fats and cholesterol, both of which, in excess, further diminish the activity of LDL receptors. Alone, diet is seldom effective. Treatment for homozygous disease is extremely difficult and includes plasmapheresis, liver or heart-liver transplantation, gene therapy trials, and various enzyme infusions. . Affected patients had total cholesterols of 500–650 mg/dl, with LDLC at 350–550 mg/dl. Analysis of LDL receptors usually demonstrates normal or slightly decreased function. . In autosomal recessive disease, mapped to chromosome 1, abnormally encoded proteins lead to dysfunction of the LDL receptor, resulting in a pattern of disease usually seen in familial hypercholesterolemia. Familial Defective APOB-100 . The disease is due to mutations in the gene on chromosome 2 at 2p24. 438 Chapter 11:Pediatric Obesity and Hyperlipidemia

. It may result in the inability of the APOB-100 ligand on LDL to properly interact with the LDL receptor, thus impairing the ability of LDL to bind to the LDL receptor. This ultimately leads to reduced plasma LDL clearance and elevated LDL levels. . The defect is inherited in an autosomal dominant fashion and is seen in approximately 1 in 600–1000, with about 5% mimicking familial hypercholesterolemia and the remainder demonstrating a slightly lower LDLC, usually 210–280 mg/dl. . Premature atherosclerotic vascular disease may be seen in these individuals. Rarely, elevated triglycerides (1500–2000 mg/dl) and pancreatitis appear due to similar impairment of VLDL clearance. Familial Combined Hyperlipidemia . The most common inherited disorder of lipid metabolism (with a prevalence of 1/50) was first described by Goldstein and associates in 1973 and is notable for a particularly complex pattern of serum lipid abnormalities. . The disease may account for as much as 10–20% of premature CAD. . It is inherited in an autosomal dominant manner, with appearance of cardiovascular disease in the fourth and fifth decades. . Exanthemas are not present. Half of patients and affected family members present with elevations of LDLC (130–180 mg/dl) and moderate elevations of triglycerides (150–300 mg/dl). The other half present with a type IV pattern, with elevated very low density lipoprotein (VLDL) triglycerides (200–400 mg/dl) and APOB (140–250 mg/dl). HDL-C may be normal or low. . Although obesity and diabetes may be associated with this disease, many individuals have a normal BMI. . The precise genetic defect is not known, but multiple genes on chromosomes 1 and 11 may result in overproduction of APOB by the liver.

Blueprint in Pediatric Endocrinology 439

Familial Hypertriglyceridemia . It has a prevalence of approximately 1 in 300 individuals, and inheritance is autosomal dominant. . Cardiovascular disease presents in the fourth or fifth decade with earlier appearance of CAD in the setting of obesity. . No single genetic locus has been identified, but recent analysis shown linkage of triglyceride level with sites on chromosomes 6, 7, and 15. . Familial hypertriglyceridemia presents with, notable for elevation of VLDL triglycerides (325–600 mg/dl) and low HDL-C levels. APOB is elevated (140–250 mg/dl). LDLC may be low. In younger individuals, there may be only modest increases in triglycerides (100–200 mg/dl). Exanthemas are not seen. . The most striking feature of this abnormality is the occasional sudden increase of triglycerides to 1000–4000 mg/dl, sometimes accompanied by pancreatitis. . This phenomenon is thought to be related to the use of steroids or the simultaneous presence of hypothyroidism. Components of metabolic syndrome may also be present. Lipoprotein Lipase Deficiency . It is a rare disease, most notable for severe chylomicronemia, eruptive exanthemas, lipemia retinalis, hepatosplenomegaly, and pancreatitis. . Classical presentation in infancy is that of creamy blood seen during a routine fasting phlebotomy. If not diagnosed early, pancreatitis may begin in the first few years of life. The elevations of triglycerides may be in the thousands of mg/dL, and not uncommonly they are in the tens of thousands. . The gene for lipoprotein lipase has been mapped to chromosome 8q22. Dozens of different mutations have been found. . A familial loss of serum lipoprotein lipase or, more rarely, an apoprotein (C-II) is responsible for this disease. 440 Chapter 11:Pediatric Obesity and Hyperlipidemia

. The inheritance is autosomal recessive and occurs with a frequency of approximately 1/100,000. Heterozygous deficiency is seen in 3–7% of Caucasians and is largely clinically silent, but it may have findings of mild disease manifested by slightly elevated triglycerides and reduced levels of HDL-C. . Except for the occurrence of pancreatitis with severe elevation of triglycerides (> 1000 mg/dL), there is no known association with CAD in these individuals. Familial Dysbetalipoproteinemia . It is a relatively rare autosomal recessive condition with a prevalence of 1/5000. . The disease results, in part, from the presence of two alleles of apolipoprotein E2 (APOE2) associated with diminished binding of VLDL to hepatic receptors. . Clinically, there is an increased incidence of CAD beginning in the third and forth decade. . Most notable are the unique eruptive exanthemas and planar exanthemas that may occur in teens but are more common in early adulthood. Small, Dense LDL Syndromes . It includes a number of genetic abnormalities such as hyperapobetalipoproteinemia and LDL subclass pattern B, as well as acquired syndromes due to oxidative stress. . These syndromes are part of the triad characterized by small LDL particles, elevated VLDL triglycerides, and low HDL-C, often referred to as atherogenic dyslipidemia. . The acquired forms of atherogenic dyslipidemia constitute the majority of findings in diabetes and metabolic syndrome. All feature normal or only mildly altered lipid profiles in most relatives but are associated with significantly increased prevalence of CAD after the third decade. At the present time, routine, inexpensive detection of small, dense LDL particles is not available in all laboratories. Blueprint in Pediatric Endocrinology 441

. Elevated lipoprotein A levels may represent an independent risk factor for CAD. The mechanism is unknown, but many isoforms of lipoprotein A resemble units of the clotting cascade, particularly plasminogen. . This suggests a role for increased thrombosis, diminished thrombolysis, or both. Measurement is difficult, and treatment is limited to the mild lowering effect of nicotinic acid, although there is no universal recommendation to begin treatment unless it accompanies another genetic dyslipidemia. Characteristics of Secondary Dyslipidemia Although the majority of children have an identifiable primary genetic disease, there are a significant number who have other conditions that secondarily cause abnormalities of blood lipids. Type 1 and type 2 diabetes mellitus have both been shown to express atherogenic dyslipidemia with elevations of VLDL triglycerides and a reduction of HDL-C, particularly in the setting of poor glucose control. In some, there may be a mild elevation of LDLC. Because diabetes is a major risk factor for CAD, there has been a special effort to manage lipids aggressively in adults with this disease. Despite the lack of clearly demonstrable findings showing an elevated risk for the development of CAD in children and adolescents with diabetes, a similarly aggressive approach would seem appropriate for this population. . Metabolic syndrome, like type 2 diabetes, appears to be increasing in the pediatric population. The lipid profile of atherogenic dyslipidemia generally shows elevations of VLDL triglycerides and low HDL-C. Unlike isolated diabetes, LDLC is usually normal. There are also relationships with overall obesity, body composition (adiposity), and the distribution of fat. Abdominal fat is associated with larger elevations of triglyceride and circulating insulin levels. For children, efforts are made to improve glycaemic control, to stabilize or eliminate obesity, and to monitor and treat hypertension when appropriate. . In hypothyroidism, elevations of LDL and VLDL lead to modest increases of both cholesterol and triglycerides. Fortunately, pharmacologic correction of hypothyroidism normalizes these abnormalities. Interestingly, HDL cholesterol is also often elevated in the setting of hypothyroidism. 442 Chapter 11:Pediatric Obesity and Hyperlipidemia

. In nephrotic syndrome, marked by proteinuria, hypoalbuminemia, and hypercholesterolemia, is a classic cause of secondary dyslipidemia. The most marked abnormality is elevation of LDLC, thought to occur as a result of hepatic overproduction of LDL and VLDL in response to the hypoalbuminemia. This may be the result of a general overproduction of proteins by the liver; it is not due to a specific effect on apolipoprotein synthesis. Overproduction of cholesterol in the liver also leads to down- regulation of the LDL receptors, resulting in diminished LDL clearance. In severe, prolonged cases of the nephrotic syndrome, triglycerides may also be elevated due to the elevated production of VLDL and to their reduced peripheral lipolysis. With treatment of the underlying disease, the lipoprotein abnormalities generally resolve. Due to the (largely) short periods of elevated serum lipids in these patients, the long-term effect on the risk of developing CAD is unknown. . Chronic renal insufficiency, however, has a significant association with cardiovascular disease with low HDL-C and elevated triglycerides. . In obstructive liver disease, LDLC is usually elevated. This is related to a number of factors including dysfunction or reduced numbers of LDL receptor sites and an inability to excrete cholesterol in bile acids. Treatment Options The rationale for treatment of children with dyslipidemia is unclear. Diet-related behavioral modification that persists into adulthood will certainly be more successful if begun during the childhood years. Whether drug intervention must begin during childhood or would be equally effective when initiated as a young adult is unknown. Diet and drug therapies for hyperlipidemia are often effective for specific lipid elevations, regardless of their origin. For instance, cholesterol-lowering agents will usually reduce serum cholesterol, whether it is related to familial hypercholesterolemia or is a product of polygenic origin. Refinements of drug use, such as timing and dosage, may improve the response significantly for individuals with specific dyslipidemia. For the general population, the American Heart Association /American Academy of Pediatrics guidelines stress a low-fat, low-cholesterol diet rich in fruit, vegetables, whole grains, and lean protein for all children over the age of 2 years. The diet should be low in saturated fat (< 10%) and cholesterol (< 300 mg/d), trans fats or Blueprint in Pediatric Endocrinology 443

partially hydrogenated oils ideally should be eliminated from the diet or should comprise less than 1% of total calories. Because trans fats occur naturally in meat and dairy products, there is not much room in the suggested diet for the additional trans fats found in many processed and fast foods. Sugar and salt intakes should be minimized also. Children over the age of 2 years should be encouraged to consume low-fat (1%) or nonfat milk and low-fat dairy products. Calorie intake should match physical activity, and physical activity should be emphasized. Physical activity in youth should include at least 60 minutes of moderate to strenuous activity daily. Screen time, including television, video games, and hand-held games, should be restricted to 2 hours or less a day. Dietary fat should not be restricted in children younger than 2 years. The emphasis in this age group, as with the older children, should be on food that is nutrient dense and in appropriate portions for age and physical activity. Breastfeeding is recommended for infants. Hypercholesterolemia With few exceptions, diet therapy is the initial treatment of children with hypercholesterolemia of any cause. The goal is to reduce saturated fat and cholesterol in the hepatocyte with the intention of promoting LDL receptor production. Because saturated fat comes principally from the diet, the strategy is often effective for mild elevations of cholesterol. Reductions of hepatic cholesterol are not as easily achieved because cholesterol is mostly synthesized in the liver. Population-wide recommendations for reducing LDLC in individuals over 2 years of age with borderline elevations of cholesterol (110–129 mg/dl) begin with the step 1 diet over 3-6 months. If normalization of LDLC (< 100 mg/dl) is not achieved, then step 2 diet is recommended with greater restrictions on fat and cholesterol intake in the Step 2 diet may require the supervision of a dietitian. In both diets, the recommended number of total calories from fat is to be the average percentage over a few days, rather than a day-by-day or meal-by-meal total. Additionally, the American Academy of Pediatrics recommends a minimum percentage of 20% of calories from fat. In children with borderline elevation of cholesterol, the Step 1 diet results in a 3–10% reduction of LDLC. An additional 4–14% LDLC reduction may be seen with the Step 2 diet. For elevations of LDLC in the abnormal range (≥ 444 Chapter 11:Pediatric Obesity and Hyperlipidemia

130 mg/dl), a smaller reduction can be expected with little or no reduction demonstrated for individuals who have large elevations of LDLC that are characteristic of familial hypercholesterolemia. In most cases, dietary intervention has little effect on HDL-C. The effectiveness of diet therapy is enhanced by addressing other factors such as smoking and obesity. The latter may require some restrictions of total calories and a prescription for regular physical exercise. The primary lipid-lowering agents recommended for pediatric hypercholesterolemia are bile acid sequestrants such as cholestyramine and colestipol. Their mechanism of action is to bind intestinal bile acids, removing them from the enterohepatic circulation and reducing hepatic cholesterol, thereby increasing the production of LDL receptors. The starting dose is usually 4 gm (i.e., 1 packet or 1 scoop) of cholestyramine or 5 gm of colestipol administered daily, 30–60 minutes before the largest meal of the day (usually dinner), with additional doses given before another meal if necessary and tolerated. Some children may become more accustomed to the gritty taste of the powder by initiating therapy with a smaller dose. The maximum dose is 16–20 gm / day. The powder is often mixed in a citrus juice, but it can be combined with almost anything. Side effects such as nausea, constipation, and bloating are frequent but are usually minor and well tolerated. Malabsorption of the fat-soluble vitamins A, E, D, and K, along with folate and iron, usually requires that these supplements be administered daily, usually in the form of an over-the-counter preparation. Hepatic function should also be monitored periodically. Bile acid sequestrants may lower total and LDL cholesterol up to 50 and 40 mg/dl, respectively, when used in children with LDLC > 130 mg/dl. The 3-hydroxy-3- methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) inhibit the rate-limiting step in endogenous cholesterol production. In a mechanism similar to that seen in sequestrants therapy, the lowering of intrahepatic cholesterol levels enhances the production of LDL receptors. Use of statin in children is currently limited to those with genetic disorders associated with extremely high LDLC, such as familial hypercholesterolemia, and to children in whom dietary therapy and sequestrants are unsuccessful. However, marked reduction in total cholesterol and LDLC (35–40% in some studies) may be achieved. In addition, elevations of HDL-C of up to 20% may also occur. Rarely, Blueprint in Pediatric Endocrinology 445

statins are combined with bile acid sequestrants to yield reductions of total cholesterol in excess of 50%. Initial statin doses are usually quite low (e.g., 5 mg of pravastatin or simvastatin once per day) and are increased only after repeating the fasting lipid profile. In most cases, the objective is to achieve a reasonable reduction of LDLC that is not necessarily within the normal range. Much concern has been generated regarding the adverse effects of statins. Hepatic transaminase elevation is seen in few children and is almost always reversible with discontinuation of the drug. Usually, restarting it after a number of weeks do not reproduce the effect. Myositis with renal failure related to myoglobinuria is a potentially serious complication that must be considered. Cataract formation is described in adults but is not a feature of statin use in children. Hepatic function tests and creatine phosphokinase (CPK) are usually monitored a few weeks after initiating therapy and periodically thereafter. An elevation of CPK is an absolute indication to discontinue the medication. At the present time, there are no generally accepted guidelines specifying who may prescribe statins. It is not our policy to limit their use to lipid specialists, but some institutions utilize this restriction. Cholesterol-absorption blockers such as ezetimibe are a new class of agents that also reduce the enterohepatic reabsorption of cholesterol. In adults, ezetimibe is used principally with the statins to provide an additional 15–25% reduction of LDLC. Some data suggest that monotherapy is effective but yields smaller reductions. Ezetimibe is not related to abnormalities of hepatic function, and it does not cause CPK elevation or malabsorption of fat soluble vitamins, making it attractive for study in children. Its availability may be affected by co administration of bile acid sequestrants. Hypertriglyceridemia . Hypertriglyceridemia usually responds to diet therapy. Reduction of total carbohydrates, the substrate for triglyceride formation, may be possible in many children who also have elevated BMI. Often, a small weight loss will result in a very significant reduction of triglycerides. . Some (but not all) statins have a measurable triglyceride-lowering effect. 446 Chapter 11:Pediatric Obesity and Hyperlipidemia

. Niacin (nicotinic acid) is thought to decrease the production of APOB and has been used successfully in children. The dose ranges from 0.5 to 3 gm/day and is usually limited by marked side effects of flushing, itching, abdominal pain, and headaches. These may be limited by the co administration of low-dose aspirin or the use of the niacin substitute inositol hexaniacinate. Additional concerns are hyperuricemia and hepatic toxicity, which require periodic laboratory testing. . Fibric acid derivatives such as gemfibrozil (600–1200 mg/day) have been used in adults to lower triglycerides, but little experience has been accumulated in children. Adverse effects such as myositis and gallstones are not uncommon and must be watched for closely, especially when used with HMG CoA reductase inhibitors. Hyperchylomicronemia Hypertriglyceridemia of hyperchylomicronemia usually, responds well to restriction of dietary fat. Often, medium-chain triglycerides may be substituted to provide sufficient calories in younger individuals. Such intervention may be needed to prevent the occurrence of pancreatitis in some individuals with lipoprotein lipase deficiency. Other Therapies In the most seriously affected individuals, such as those with homozygous familial hypercholesterolemia, diet and medication may not have any impact on LDLC. Other methods of treatment in these circumstances include liver transplantation (i.e., transplantation of LDL receptors) and plasmapheresis or LDL aphaeresis to remove LDLC from the serum. Experimental approaches with gene therapy have been explored for these severely affected patients. References and Further Reading

1. Flynn MA, McNeil DA, Maloff B, et al. Reducing obesity and related chronic disease risk in children and youth: a synthesis of evidence with ‗best practice‘ recommendations. Obes Rev. 2006; 1:7-66. 2. Uli N, Sundararajan S, Cuttler L. Treatment of childhood obesity. Curr Opin Endocrinol Diab Obes. 2008; 15:37-47. 3. Whitlock EP, Williams SB, Gold R, Smith PR, Shipman SA. Screening and interventions for childhood overweight: a summary of evidence for the US Preventive Services Task Force. Pediatrics. 2005; 116. Blueprint in Pediatric Endocrinology 447

4. Mayer-Davis EJ. Type 2 diabetes in youth: epidemiology and current research toward prevention and treatment. J Amer Diet Assoc. 2008; 108. 5. Sinha R, Fisch G, Teague B, et al. Prevalence of impaired glucose tolerance among children and adolescents with marked obesity. N Engl J Med. 2002; 346:802-810. 6. Flynn JT. Pediatric hypertension: recent trends and accomplishments, future challenges. Am J Hypertens. 2008; 21:605-612. 7. Daniels SR, Greer FR, Committee on N. Lipid screening and cardiovascular health in childhood. Pediatrics. 2008; 122:198-208.

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