DOCSLIB.ORG

Parathyroid Disorders THOMAS C

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Parathyroid Disorders THOMAS C Parathyroid Disorders THOMAS C. MICHELS, MD, MPH, Madigan Army Medical Center, Tacoma, Washington KEVIN M. KELLY, MD, MBA, Carl R. Darnall Army Community Hospital, Fort Hood, Texas Disorders of the parathyroid glands most commonly present with abnormalities of serum calcium. Patients with primary hyperparathyroidism, the most common cause of hypercalcemia in outpatients, are often asymptomatic or may have bone disease, nephrolithiasis, or neuromuscular symptoms. Patients with chronic kidney disease may develop secondary hyperparathyroidism with resultant chronic kidney disease-mineral and bone disorder. Hypo- parathyroidism most often occurs after neck surgery; it can also be caused by autoimmune destruction of the glands and other less common problems. Evaluation of patients with abnormal serum calcium levels includes a history and physical examination; repeat measurement of serum calcium level; and measurement of creatinine, magne- sium, vitamin D, and parathyroid hormone levels. The treatment for symptomatic primary hyperparathyroidism is parathyroidectomy. Management of asymptomatic primary hyperparathyroidism includes monitoring symptoms; serum calcium and creatinine levels; and bone mineral density. Patients with hypoparathyroidism require close monitoring and vitamin D (e.g., calcitriol) replacement. (Am Fam Physician. 2013;88(4):249-257. Copyright © 2013 American Academy of Family Physicians.) CME This clinical content he four parathyroid glands, located 84-amino acid peptide. PTH increases serum conforms to AAFP criteria posterior to the thyroid gland, reg- calcium levels through direct action on bone for continuing medical education (CME). See CME ulate calcium homeostasis through and the kidneys. It stimulates osteoclasts to Quiz on page 227. release of parathyroid hormone resorb bone and mobilize calcium into the T (PTH). Because most parathyroid disorders blood. In the kidneys, PTH acts to reduce Author disclosure: No rel- evant financial affiliations. present with abnormalities of serum cal- calcium clearance and stimulates synthesis cium, they commonly appear in differential of 1,25-dihydroxyvitamin D, which stimu- diagnoses. Therefore, understanding the lates calcium absorption in the gastrointes- presentation and principles of evaluation of tinal tract (Figure 1).1,2 In their normal state, parathyroid disorders is important in pri- the glands function to keep serum calcium mary care. levels within a consistent and tightly con- trolled range. The glands synthesize and Pathophysiology store the PTH, allowing it to respond within The parathyroid glands respond to low serum minutes of hypocalcemia. Sustained hypo- calcium levels by releasing PTH, which is an calcemia leads to cellular replication and SORT: KEY RECOMMENDATIONS FOR PRACTICE Evidence Clinical recommendation rating References Patients with primary hyperparathyroidism and symptoms or signs should C 25, 26 undergo surgical removal of their parathyroid gland(s). Patients with primary hyperparathyroidism who do not undergo C 15, 26 parathyroidectomy should have serum calcium and creatinine levels measured annually, and three-site (i.e., hip, spine, and forearm) bone density measurement every one to two years. Family members of a patient with multiple endocrine neoplasia type 2 C 10, 21 should be tested for the patient’s specific genetic mutation. A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evi- dence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to http://www.aafp.org/afpsort. Downloaded from the American Family Physician Web site at www.aafp.org/afp. Copyright © 2013 American Academy of Family Physicians. For the private, Augustnoncommercial 15, 2013 use of◆ Volumeone individual 88, Numberuser of the 4 Web site. All other rights reserved.www.aafp.org/afp Contact [email protected] for copyright questionsAmerican and/or Family permission Physician requests. 249 Parathyroid Disorders increased mass of the glands. Calcium and 1,25-dihydroxyvitamin D provide negative feedback at the parathyroid glands to inhibit PTH release. One normal gland is sufficient for adequate secretion of PTH to maintain normal calcium levels.1,3,4 Parathyroid disorders most commonly present with serum calcium abnormalities. Decreased Rarely, patients can present with a neck mass serum calcium or for evaluation of a family history of para- thyroid or related disorders. The estimated incidence of primary hyperparathyroidism is approximately 25 cases per 100,000 persons 5-7 Increased serum calcium per year in outpatients of Western countries, with a prevalence of one to four per 1,000 per- 8 Parathyroid sons. Hypoparathyroidism most commonly glands occurs after inadvertent damage or removal of parathyroid glands during neck surgery; Bone estimates for the occurrence of this surgical complication range from 0.5% to 6.6%, with higher rates after repeat neck surgery.1,9 Mul- Parathyroid hormone tiple endocrine neoplasia type 1 (MEN-1) and type 2 (MEN-2), which often include parathy- roid neoplasia, each occur in about two per Kidney 10 Increased bone 100,000 persons per year. Parathyroid can- resorption cer is rare, with an incidence of approximately four per 10 million persons per year.11 Hyperparathyroidism Increased calcium reabsorption PRIMARY Primary hyperparathyroidism, the most common cause of hypercalcemia in outpa- Intestine tients, is often discovered incidentally dur- 25-hydroxyvitamin D to ing evaluation of serum electrolyte levels. 1,25-dihydroxyvitamin D Before the easily available measurement of Increased calcium serum calcium levels, patients presented with absorption in the 4,12,13 gastrointestinal tract a spectrum of symptoms (Table 1). Most Negative feedback/ patients today are asymptomatic, with neph- decreased activity rolithiasis occurring in up to 15% of patients, Positive feedback/ bone disease (formerly osteitis fibrosa cys- stimulation tica) occurring in 2% of patients, and neu- romuscular symptoms occurring rarely.3,14,15 ILLUSTRATION BY DAVID KLEMM Figure 1. Control of mineral metabolism by parathyroid hormone Although marked symptoms are uncommon (PTH). Calcium-sensing receptors of parathyroid cells respond to in Western countries, it is important to be serum calcium level and change with increased release (hypocal- aware that subtle and nonspecific symptoms cemia) or suppression (hypercalcemia) of PTH. PTH stimulates bone may be present.14-16 Other causes of hypercal- resorption, which increases serum calcium and phosphorus. In the cemia are listed in Table 2.3,5,8,17,18 kidney, PTH stimulates reabsorption of calcium and promotes phos- phorus excretion. PTH also helps convert 25-hydroxyvitamin D to Overall, 85% of patients with primary 1,25-dihydroxyvitamin D in the kidneys, which then increases intesti- hyperparathyroidism have a single adenoma. nal transport of calcium and phosphorus. Risk factors for primary hyperparathyroid- Information from references 1 and 2. ism include a history of neck radiation, age 250 American Family Physician www.aafp.org/afp Volume 88, Number 4 ◆ August 15, 2013 Table 1. Symptoms Associated with Hypercalcemia Organ system Most common symptoms and possible diagnoses older than 50 years, and female sex; women Cardiovascular Angina, dyspnea, palpitations, syncope are twice as likely as men to develop pri- Possible diagnoses: diastolic dysfunction, dysrhythmias, mary hyperparathyroidism. Multiglandu- hypertension, left ventricular hypertrophy, vascular calcification lar hyperplasia accounts for 10% to 15% of patients with primary hyperparathyroid- Gastrointestinal Anorexia, constipation, epigastric pain, nausea, vomiting ism, and carcinoma accounts for 1% or less. Possible diagnoses: pancreatitis, peptic ulcer disease There are also uncommon familial causes, Neuromuscular Anxiety, confusion, depression, fatigue, forgetfulness, such as MEN-1 and MEN-2A; persons with impaired vision, insomnia, lethargy, weakness these conditions may have parathyroid ade- Possible diagnoses: corneal calcification, delirium, mild nomas or asymmetric hyperplasia.8,19 cognitive impairment SECONDARY Renal Polydipsia, polyuria, renal colic Secondary hyperparathyroidism most com- Possible diagnoses: nephrocalcinosis, nephrolithiasis, nephrogenic diabetes insipidus monly occurs because of decreased levels of 1,25-dihydroxyvitamin D, hyperphospha- Skeletal Arthralgia, bone pain, fractures temia, and hypocalcemia in the setting of Possible diagnoses: bone disease, insufficiency chronic kidney disease. Other causes include fractures, osteomalacia, osteoporosis vitamin D deficiency secondary to low Information from references 4, 12, and 13. dietary intake, lack of sun exposure, mal- absorption, liver disease, and other chronic illness.20 In some patients with advanced renal failure, hypercalcemia is due to progres- Table 2. Causes of Hypercalcemia sion from appropriate parathyroid hyper- plasia to autonomous overproduction of Parathyroid hormone–dependent PTH, a disorder termed tertiary hyperpara- Primary hyperparathyroidism thyroidism.12,20 Familial hypocalciuric hypercalcemia Patients with normocalcemic hyper- Lithium-associated parathyroidism may present with low bone Tertiary hyperparathyroidism density, osteoporosis, or a fragility fracture. Genetic disorders (e.g., multiple endocrine neoplasia type 1 or type 2A, familial hyperparathyroidism) Many of these patients will probably evolve
Load more

Recommended publications
  • Thyroid Gland Parathyroid Glands
    Human Physiology Course Thyroid Gland Parathyroid Glands Assoc. Prof. Mária Pallayová, MD, PhD [email protected] Department of Human Physiology, UPJŠ LF April 13, 2020 (10th week – Summer Semester 2019/2020) Hormones and Functions Thyroid gland Parathyroids Thymus Adrenal glands Endocrine pancreas Ovaries, Testes Pineal Pituitary Hypothalamus-Pituitary Axis GIT, adipose tissue, brain, heart, kidney, ... Hormones and Functions Thyroid gland Parathyroids Thymus Adrenal glands Endocrine pancreas Ovaries, Testes Pineal Pituitary Hypothalamus-Pituitary Axis GIT, adipose tissue, brain, heart, kidney, ... Lecture Outline Functional anatomy of the thyroid gland Synthesis, secretion, and metabolism of the thyroid hormones The mechanism of thyroid action Role of the thyroid hormones in development, growth, and metabolism Thyroid hormone deficiency and excess in adults Physiology of the parathyroids Functional Anatomy of the Thyroid Gland two lobes + isthmus (just below the cricoid cartilage) attached to the trachea by connective tissue A normal THGL in a healthy adult weighs about 15-20 g. Functional Anatomy of the Thyroid Gland arterial blood supply: from a superior and an inferior thyroid a., which arise from the external carotid and subclavian a., respectively. venous blood supply: a series of thyroid veins drain into the ext. jugular and innominate vv. ( a rich blood supply to the thyroid gland w/ a higher rate of blood flow per gram than even that of the kidneys). innervation: adrenergic innervation from the cervical ganglia; cholinergic innervation from the n. vagus (regulation of vasomotor function to increase the delivery of TSH, iodide, and metabolic substrates to the THGL). Functional Anatomy of the Thyroid Gland The colloid (a thick, gel-like substance) is a solution composed primarily of thyroglobulin (10-25% the high viscosity), a large protein that is a storage form of the thyroid hormones.
    [Show full text]
  • The Fine Structure of the Parathyroid Gland*
    The Fine Structure of the Parathyroid Gland* BY JERRY STEVEN TRIER, M.D. (From the Department of Anatomy, University of Washington School of Medicine, Seattle) PLATES 3 TO 10 (Received for publication, July 29, 1957) ABSTRACT The fine structure of the parathyroid of the macaque is described, and is cor- related with classical parathyroid cytology as seen in the light microscope. The two parenchymal cell types, the chief cells and the oxyphil cells, have been recognized in electron mierographs. The chief cells contain within their cyto- plasm mitochondria, endoplasmic reticulum, and Golgi bodies similar to those found in other endocrine tissues as well as frequent PAS-positive granules. The juxtanuclear body of the light microscopists is identified with stacks of parallel lamellar elements of the endoplasmic rcticulum of the ergastoplasmic or granular type. Oxyphll cells are characterized by juxtanuclear bodies and by numerous mito- chondria found throughout their cytoplasm. Puzzling lamellar whorls are described in the cytoplasm of some oxyphil cells. The endothelium of parathyroid capillaries is extremely thin in some areas and contains numerous fenestrations as well as an extensive system of vesicles. The possible significance of these structures is discussed. The connective tissue elements found in the perivascular spaces of macaque parathyroid are described. INTRODUCTION Other contributions to the present concepts con cerning the human parathyroid can be found in the It is the purpose of the present paper to report some observations on the fine structure of the reports of Bergstrand (7), Morgan (34), Pappen- parathyroid gland employing the electron micro- heimer and Wilens (45), Castleman and Mallory (10), and Gilmour (20).
    [Show full text]
  • Thyroid & Parathyroid Glands
    THYROID & PARATHYROID GLANDS Objectives: ◧ Editing file • Describe the histological structure of ◧ thyroid & parathyroid glands. Important • Identify and correlate between the different ◧ Doctor notes / Extra endocrine cells in thyroid gland and their functions. • Describe the functional structure of the parathyroid cells. 438 Histology Team Endocrine Block THYROID GLAND STROMA 1- Capsule: dense irregular collagenous C.T. 2- Septa (Interlobular septa) 3- Reticular fibers: Thin C.T. composed mostly of reticular fibers with rich capillary plexus surrounds each thyroid follicle. PARENCHYMA Are the structural and functional units of the thyroid gland. 1- Simple cuboidal epithelium: 2- Colloid: central colloid-filled lumen. a- Follicular (principal) cells b- Parafollicular cells (C cells) (Clear cells) - Pale-stained cells (Clear Cells). (Polygonal/pyramidal cells) N.B. Each follicle is - Simple cuboidal cells. - Found singly or in clusters in between the follicular cells. - Round nucleus with prominent nucleoli. surrounded by thin - Their apices do not reach the lumen of the follicle. L/M: - Basophilic cytoplasm. basal lamina. - Are larger than follicular cells (2-3 times).(larger but less in number) - Apical surface reaches the lumen of the (Acidophilic) - Only 0.1% of the epithelial cells. thyroid follicle. - Have round nucleus - Mitochondria. - RER. (synthesis of thyroglobulin) - Supranuclear Golgi Complex. - Mitochondria. E/M: - Numerous apically-located lysosomes. - RER (moderate). - Numerous dispersed small vesicles - Well-developed Golgi. - The vesicles contain newly formed thyroglobulin. - Numerous apical short microvilli. Function: Synthesis of thyroid hormones (T4 & T3). Secrete calcitonin. 438 Histology Team - Endocrine Block 2 PARATHYROID GLAND They are 4 glands on the posterior of thyroid gland. STROMA 1- Capsule: Each gland has its Thin capsule.
    [Show full text]
  • Primary Hyperparathyroidism
    Primary Hyperparathyroidism The parathyroid glands are 4 glands that reside within the thyroid glands: there are two parathyroid glands attached to each thyroid gland. The thyroid/parathyroid glands lie on either side of the trachea (wind pipe) about midway down the neck. The job of the parathyroid glands is to regulate calcium in the body. They secrete a hormone called parathyroid hormone (PTH), and this hormone draws calcium out of the bone where it is stored, as well as acting on the kidney and intestine to increase blood calcium. This is a normal process in response to fluctuations in blood calcium levels. The calcium in the blood is regulated by PTH (increases blood calcium) and calcitonin (a hormone secreted by the thyroid gland to decrease calcium) in order to keep it within a normal range. When the calcium gets too high or too low, symptoms arise. The most common symptoms of high calcium are increased thirst and urination. Other signs include: lethargy, weakness, diarrhea, inappetance, weight loss, tremors or stiffness. In about 50% of dogs with high calcium, urinary stones +/- urinary tract infection is present. Tumors (enlargement) of the parathyroid gland are typically not malignant, but they do over-secrete PTH. In 90% of cases only one of the four glands is enlarged. By one gland enlarging and over-secreting PTH, the three other glands typically shrink and temporarily stop functioning. Parathyroid tumors are suspected based on consistent blood work that shows elevated or normal PTH in the face of elevated calcium (the normal feedback mechanism would mean that when calcium is high, PTH is not needed and therefore is low).
    [Show full text]
  • Primary Hyperparathyroidism
    Primary Hyperparathyroidism National Endocrine and Metabolic Diseases Information Service What is primary What are the parathyroid hyperparathyroidism? glands? Primary hyperparathyroidism is a disorder The parathyroid glands are four pea-sized U.S. Department of the parathyroid glands, also called glands located on or near the thyroid gland of Health and parathyroids. “Primary” means this disorder in the neck. Occasionally, a person is born Human Services originates in the parathyroid glands. In with one or more of the parathyroid glands primary hyperparathyroidism, one or more in another location. For example, a gland NATIONAL INSTITUTES of the parathyroid glands are overactive. may be embedded in the thyroid, in the OF HEALTH As a result, the gland releases too much thymus—an immune system organ located parathyroid hormone (PTH). The disorder in the chest—or elsewhere around this area. includes the problems that occur in the rest In most such cases, however, the parathyroid of the body as a result of too much PTH—for glands function normally. example, loss of calcium from bones. In the United States, about 100,000 people develop primary hyperparathyroidism each year.1 The disorder is diagnosed most often in people between age 50 and 60, and women are affected about three times as often as men.2 Secondary, or reactive, hyperparathyroidism can occur if a problem such as kidney failure causes the parathyroid glands to be overactive. Parathyroid glands Thyroid gland The parathyroid glands are located on or near the thyroid gland in the neck. 1Bilezikian JP. Primary hyperparathyroidism. In: DeGroot LJ, ed.; Arnold A, section editor.
    [Show full text]
  • The Endocrine System
    PowerPoint® Lecture Slides The Endocrine System: An Overview prepared by Leslie Hendon University of Alabama, Birmingham • A system of ductless glands • Secrete messenger molecules called hormones C H A P T E R 17 • Interacts closely with the nervous system Part 1 • Endocrinology The Endocrine • Study of hormones and endocrine glands System Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Endocrine Organs Location of the Major Endocrine Glands Pineal gland • Scattered throughout the body Hypothalamus Pituitary gland • Pure endocrine organs are the … Thyroid gland • Pituitary, pineal, thyroid, parathyroid, and adrenal Parathyroid glands glands (on dorsal aspect of thyroid gland) • Organs containing endocrine cells include: Thymus • Pancreas, thymus, gonads, and the hypothalamus Adrenal glands • Plus other organs secrete hormones (eg., kidney, stomach, intestine) Pancreas • Hypothalamus is a neuroendocrine organ • Produces hormones and has nervous functions Ovary (female) Endocrine cells are of epithelial origin • Testis (male) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 17.1 Hormones Control of Hormones Secretion • Classes of hormones • Amino acid–based hormones • Secretion triggered by three major types of • Steroids—derived from cholesterol stimuli: • Basic hormone action • Humoral—simplest of endocrine control mechanisms • Circulate throughout the body in blood vessels • Secretion in direct response to changing • Influences only specific tissues— those with ion or nutrient levels in the blood target cells that have receptor molecules for that hormone • Example: Parathyroid monitors calcium • A hormone can have different effects on • Responds to decline by secreting different target cells (depends on the hormone to reverse decline receptor) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc.
    [Show full text]
  • Preoperative and Intraoperative Methods of Parathyroid Gland Localization and the Diagnosis of Parathyroid Adenomas
    molecules Review Preoperative and Intraoperative Methods of Parathyroid Gland Localization and the Diagnosis of Parathyroid Adenomas Jacek Baj 1,*, Robert Sitarz 1,2 , Marek Łokaj 2, Alicja Forma 1 , Marcin Czeczelewski 3 , Amr Maani 1 and Gabriella Garruti 4 1 Chair and Department of Anatomy, Medical University of Lublin, 20-950 Lublin, Poland; [email protected] (R.S.); [email protected] (A.F.); [email protected] (A.M.) 2 Department of Surgery, Center of Oncology of the Lublin Region St. Jana z Dukli, 20-090 Lublin, Poland; [email protected] 3 Chair and Department of Forensic Medicine, Medical University of Lublin, 20-950 Lublin, Poland; [email protected] 4 Section of Endocrinology, Andrology and Metabolic Diseases, Department of Emergency and Organ Transplantations, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy; [email protected] * Correspondence: [email protected]; Tel.: +48-662-094-014 Received: 24 February 2020; Accepted: 8 April 2020; Published: 9 April 2020 Abstract: Accurate pre-operative determination of parathyroid glands localization is critical in the selection of minimally invasive parathyroidectomy as a surgical treatment approach in patients with primary hyperparathyroidism (PHPT). Its importance cannot be overemphasized as it helps to minimize the harmful side effects associated with damage to the parathyroid glands such as in hypocalcemia, severe hemorrhage or recurrent laryngeal nerve dysfunction. Preoperative and intraoperative methods decrease the incidence of mistakenly
    [Show full text]
  • Anatomy of Endocrine System
    Anatomy of Endocrine system Introduction, Pituitary gland and Thyroid gland Prepared by Dr. Payal Jain Endocrine System I. Introduction A. Considered to be part of animals communication system 1. Nervous system uses physical structures for communication 2. Endocrine system uses body fluids to transport messages (hormones) II. Hormones A. Classically, hormones are defined as chemical substances produced by ductless glands and secreted into the blood supply to affect a tissue distant from the gland, but now it is understood that hormones can be produced by single cells as well. 1. epicrine a. hormones pass through gap junctions of adjacent cells without entering extracellular fluid 2. paracrine a. hormones diffuse through interstitial fluid (e.g. prostaglandins) 3. endocrine a. hormones are delivered via the bloodstream (e.g. growth hormone Different endocrine glands with cell Organ Division arrangement Cell arrangement/morphology Hormone Hypophysis Adenohypophysis Pars distalis Cells in cords around large-bore capillaries: Acidophils Growth hormone, prolactin Basophils ACTH, TSH, FSH, LH Pars intermedia Mostly basophilic cells around ACTH, POMC cystic cavities Pars tuberalis Narrow sleeve of basophilc cells LH around infundibulum Neurohypophysis Pars nervosa Nerve fibers and supporting cells Oxytocin and (pituicytes) vasopressin (produced in hypothalamus) Infundibulum Nerve fibers (traveling from hypothalamus to pars nervosa) Pancreas Islet of Langerhans Irregularly arranged cells with Insulin, glucagon many capillaries Follicles: Simple
    [Show full text]
  • Endocrine Glands [PDF]
    Histology of Skin and Endocrine glands Skin and Endocrine glands • Skin • Thyroid • Parathyroid gland • Adrenal gland • Pituitary gland • Pineal gland Skin • Layers of skin • Epidermis • Five layers • Dermis • Two layers Junction • Dermal papilla • Epidermal peg (rete pegs) Skin…. • Epidermis - 1.Stratum basale • Single layer of columnar cells 2.Stratum spinosum • Several layers of polyhedral cells, spine like process, tonofilament 3.Stratum granulosum • Keratohyline granules 4.Stratum lucidum • Homogeneous keratin, fusiform cells 5.Stratum corneum-non nucleated keratinized dead cells Skin…… • Cells of epidermis -Keratinocytes- 90%,able to keratinization -Cells of Langherhans- present in st.spinosum, clear cytoplasmic process, antigen producing cell -Melamocytes-pigmented cell in basal layer, many cytoplasmic process. Produce Melanin -Merkel cells- sensory cell Skin….. Dermis • Papillary layer • Tactile papilla • Vascular papilla • Collagen fibre • Reticular layer Collagen fibre • Sweat glands • Sebaceous glands • Hairs Skin…… • Thick skin • Thin skin Thyroid gland 1.Capsule 2.Parenchyma • thyroid follicle -Structural & functional unite -Epithelium-simple cuboidal cells (follicular cells), synthesis thyroxin hormone -cell size varies with activeness -Lumen of thyroid follicle filled with colloid -Parafollicular cells (“C” Cells) Present at margin or inter follicular space, Calcitonin 3.Stroma- connective tissue, septa, blood vessels Parathyroid gland • Chief cells • Polygonal shape, round nucleus, synthesis Parathormone • Oxyphill cells-
    [Show full text]
  • The Normal Thyroid Gland
    1 THE NORMAL THYROID GLAND EMBRYOLOGY before lumen formation and colloid secretion The thyroid anlage appears as a bilobate ve- can be detected (4,5). sicular structure at the foramen cecum of the It has recently become clear that thyroid gland tongue. It then descends as a component of the organogenesis and the differentiation of follicular thyroglossal duct to reach its definitive position in cells are directed by the concerted action of a series the neck (fig. -). After involution of the thyro- of transcription factors, while thyroid-stimulating glossal duct, the thyroid anlage begins to expand hormone (TSH) influences thyroid differentiation laterally to form the thyroid lobes (–3). only after the anatomic outline of the gland is well Microscopically, the initially solid thyroid established. The most important of these tran- anlage begins to form cords and plates of fol- scription factors are thyroid transcription factor licular cells during the 9th gestational week. A (TTF)- (Nkx2-), TTF-2 (Foxe), PAX8, and Hhex small lumen appears within the follicles by the (6). Although these factors are also expressed and 0th week, with colloid secretion becoming influence differentiation in other developing tis- evident by the 2th week. By the 4th week, sues, all four are coexpressed only in the thyroid the gland already consists of well-developed anlage (6). Since they regulate the expression follicles lined by follicular cells and containing of thyroid-specific genes (e.g., those responsible thyroglobulin-positive colloid in their lumens for the production of thyroid peroxidase and (figs. -2–-3). Labeled amino acid studies have thyroglobulin) they are important not only for shown that thyroglobulin synthesis begins at a organogenesis but for the functional differen- very early stage, when the thyroid gland is still tiation of the gland in later stages of prenatal a solid mass at the base of the tongue, and long development and postnatally (6,7).
    [Show full text]
  • What Is Endocrine Surgery?
    What is Endocrine Surgery? Endocrine Surgery is the discipline of surgical management of endocrine disorders, including the understanding of disease process, technical mastery and comprehensive care of surgical endocrine diseases of the neck and abdomen. Thyroid The thyroid gland is a butterfly shaped gland in the center of the neck. The thyroid gland produces the thyroid hormones T3 (triiodothyronine) and T4 (thyroxine). These hormones regulate the growth and function of many systems of the body and they set the pace of the metabolism. Hypothyroidism is when the thyroid under produces hormones. Hashimoto’s thyroiditis is an auto-immune disease in which the immune system attacks the thyroid gland resulting in hypothyroidism. Hyperthyroidism is overproduction of thyroid hormone. Graves’ disease is also an autoimmune disease however in this case the result is excessive thyroid hormone levels and hyperthyroidism. Goiter is a term for enlargement of the thyroid gland. The enlargement can be diffuse, due to one nodule or due to multiple nodules. Nodules are growths within the thyroid gland. Nodules can be benign or malignant. Nodules are evaluated with a neck ultrasound. Nodules greater than 1cm or with suspicious features should be sampled with a fine needle biopsy to rule out a thyroid cancer. Larger nodules can exert pressure on local structures such as the trachea, esophagus, and nerve to the voice resulting in trouble breathing, swallowing or speaking. Thyroid surgery is indicated when nodules cause compressive symptoms, when nodules are cancerous and when nodules are suspicious on fine needle aspiration. Thyroid cancer is cancer originating in the thyroid gland. There are 4 types of thyroid cancer: papillary carcinoma, follicular carcinoma, medullary carcinoma and anaplastic thyroid cancer.
    [Show full text]
  • Rodriguez, Elvira Fernandez and Jose M. Valdivielso Eva Parisi, Yolanda Almadén, Mercé Ibarz, Sara Panizo, Anna Cardús, Maria
    Eva Parisi, Yolanda Almadén, Mercé Ibarz, Sara Panizo, Anna Cardús, Mariano Rodriguez, Elvira Fernandez and Jose M. Valdivielso Am J Physiol Renal Physiol 296:1291-1296, 2009. First published Apr 8, 2009; doi:10.1152/ajprenal.90557.2008 You might find this additional information useful... This article cites 25 articles, 12 of which you can access free at: http://ajprenal.physiology.org/cgi/content/full/296/6/F1291#BIBL Updated information and services including high-resolution figures, can be found at: http://ajprenal.physiology.org/cgi/content/full/296/6/F1291 Additional material and information about AJP - Renal Physiology can be found at: http://www.the-aps.org/publications/ajprenal This information is current as of June 2, 2009 . Downloaded from ajprenal.physiology.org on June 2, 2009 AJP - Renal Physiology publishes original manuscripts on a broad range of subjects relating to the kidney, urinary tract, and their respective cells and vasculature, as well as to the control of body fluid volume and composition. It is published 12 times a year (monthly) by the American Physiological Society, 9650 Rockville Pike, Bethesda MD 20814-3991. Copyright © 2005 by the American Physiological Society. ISSN: 0363-6127, ESSN: 1522-1466. Visit our website at http://www.the-aps.org/. Am J Physiol Renal Physiol 296: F1291–F1296, 2009. First published April 8, 2009; doi:10.1152/ajprenal.90557.2008. N-methyl-D-aspartate receptors are expressed in rat parathyroid gland and regulate PTH secretion Eva Parisi,1 Yolanda Almade´n,3 Merce´ Ibarz,4 Sara Panizo,1 Anna Cardu´s,1 Mariano Rodriguez,3 Elvira Fernandez,2* and Jose M.
    [Show full text]