Clin Chest Med 24 (2003) 583–606

Critical issues in endocrinology

Philip A. Goldberg, MD, Silvio E. Inzucchi, MD*

Section of Endocrinology, Yale University School of Medicine, TMP 534, 333 Cedar Street, New Haven, CT 06520, USA

Endocrine emergencies are commonly encountered The underlying mechanism for DKA and HHS is in the intensive care unit (ICU). This article focuses on the reduced net activity of circulating insulin, usually several important endocrine emergencies, including with concurrent stimulation of counter-regulatory hor- diabetic hyperglycemic states, adrenal insufficiency, mone activity (eg, glucagon, catecholamines, gluco- myxedema coma, thyroid storm, and pituitary apo- corticoids [GC]). As shown in Fig. 1, these hormonal plexy. Other endocrine issues that are related to inten- changes lead to increased glucose production and sive care, such as intensive insulin therapy, relative decreased peripheral glucose use. Hyperglycemia adrenal insufficiency, and thyroid function test abnor- ensues, which leads to a vigorous osmotic diuresis malities also are covered in detail. Because of space which precipitates volume contraction and severe limitations, additional endocrinologic emergencies in- electrolyte losses [12]. In the setting of absolute insulin cluding hypoglycemia, calcium disorders, and fluid deficiency (ie, DKA), accelerated lipolysis and fatty and electrolyte disorders are not included (for reviews acid oxidation also generate ketoacidosis [13].In see references [1–7]). general, DKA afflicts patients who have type 1 diabe- tes, whereas HHS occurs in patients who have type 2 diabetes; however, there is substantial overlap between Critical issues in metabolism these two clinical syndromes. In clinical practice, HHS can present with variable degrees of ketosis and Diabetic hyperglycemic crises: diabetic ketoacidosis acidosis. Conversely, DKA is being seen with increas- and hyperosmolar hyperglycemic states ing frequency in patients who have type 2 diabetes, with a predilection for obese African Americans [14]. Diabetic hyperglycemic crises are commonly en- Most hyperglycemic crises have an identifiable countered in the ICU. Diabetic ketoacidosis (DKA) precipitating event. Infections trigger up to 50% of occurs with an annual incidence of four to eight cases [10]. Pneumonia, urinary tract infections (UTIs), episodes per 1000 diabetic patients [8,9]. It accounts and sepsis are common precipitants, as are common for more than 100,000 yearly hospital admissions [10], viral triggers, such as gastroenteritis and upper respi- with total costs (at more than $13,000 per admission) ratory infections. Inadequate insulin treatment, includ- that exceed $1.3 billion per year [11]. The incidence ing medication noncompliance and insulin pump and economic impact of hyperosmolar hyperglycemic failure, accounts for an additional 20% to 40% of states (HHS) are more difficult to ascertain, because of cases [10]. Table 1 lists some of the more common a lack of population-based studies. Although hospital precipitants for diabetic hyperglycemic crises. admission rates for HHS are likely lower than those for DKA [10], the growing type 2 diabetes epidemic Diagnosis suggests that the incidence of HHS is increasing. The presence of DKA or HHS is suggested by a history of polyuria, polydipsia, nausea, vomiting, or dehydration in the setting of known diabetes. DKA/ * Corresponding author. HHS may also be the initial presentation of new E-mail address: [email protected] diabetes. Because of the discomfort that is induced (S.E. Inzucchi). by acidosis, DKA typically evolves within 24 hours,

0272-5231/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0272-5231(03)00091-1 584 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

Fig. 1. Pathogenesis of diabetic hyperglycemic states. whereas HHS may progress over several days [15]. For variable degrees of lethargy, mental status changes, this reason, patients who have HHS typically present and dehydration; the latter is suggested by decreased with more severe dehydration and electrolyte distur- skin turgor, dry mucous membranes, tachycardia, and bances. Focal neurologic symptoms or seizures may be orthostatic hypotension. Abdominal pain is common seen in severe cases [16]. On physical examination, in DKA and may reflect delayed gastric emptying or patients who have hyperglycemic crises present with intestinal ileus [17]; this symptom is less commonly seen in HHS. The presence of ketoacidosis is sug- gested by the presence of ‘‘acetone breath’’ or rapid, deep Kussmaul respirations. Table 1 The diagnosis of hyperglycemic crises is usually Known precipitants of diabetic hyperglycemic crises straightforward. The presence of hyperglycemia in the % of Cases Precipitating event proper clinical setting should trigger the clinician to 30–50% Infections: Viral infections, test for serum and urine ketones and to obtain arterial pneumonia, UTI, sepsis blood gases. Follow-up serologic evaluation should 20–40% Inadequate insulin therapy include a complete blood count with differential, 3–6% Myocardial ischemia/infarction chemistries (including divalent cations), serum osmo- < 2% Cerebrovascular accident lality, liver and pancreatic function tests, and cardiac Intracranial bleeding enzymes. Bacterial cultures of blood, urine, and other Pulmonary embolus sources should be obtained, along with a urinalysis, Intestinal thrombosis or obstruction chest radiograph, and 12-lead ECG. A full septic work- Acute pancreatitis up should be considered in all patients, particularly Alcohol intoxication Acute renal failure, peritoneal dialysis infants. Recent laboratory criteria that are endorsed by Hyperthermia or hypothermia the American Diabetes Association (ADA) for the Severe burns diagnosis of DKA and HHS [18] are displayed in Endocrine disorders: thyroid Table 2. In general, DKA is diagnosed when plasma storm, Cushing’s syndrome glucose is greater than 250 mg/dL and arterial pH is Total parenteral nutrition less than 7.30 in the setting of detectable urine/serum Drugs: b-blockers, calcium channel ketones. DKA severity may be graded using pH, blockers, diuretics, corticosteroids, bicarbonate, and other clinical criteria (see Table 2). antipsychotics, phenytoin, cimetidine HHS is diagnosed when plasma glucose is greater P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 585

Table 2 Laboratory diagnosis and classification of DKA and HHS Mild DKA Moderate DKA Severe DKA HHS Plasma glucose (mg/dL) > 250 >250 >250 >600 Serum osm (mosm/kg) Variable Variable Variable >320 Urine/serum ketones Positive Positive Positive Weak/negative Arterial pH 7.25–7.30 7.00–7.24 < 7.00 >7.30 Serum HCO3 (mEq/L) 15–18 10–15 < 10 >15 Anion gap (mEq/L) >10 >12 >12 < 12 From Kitabachi AE, et al. Technical review. Management of hyperglycemic crises in patients with diabetes. Diabetes Care 2001;24:131–55; with permission. than 600 mg/dL and serum osmolarity is greater than itate cerebral edema through accelerated fluid shifts 320 mosm/kg. The term ‘‘HHS’’ [15] is now preferred into the brain [12]. over ‘‘hyperglycemic hyperosmolar nonketotic coma’’ to emphasize two important clinical points: (1) mental Insulin. Insulin therapy is an essential component of status changes usually occur in the absence of frank therapy for DKA, and is useful in most cases of HHS. coma, and (2) some degree of ketosis may be present Although severe insulin resistance is present in both in HHS. conditions, supraphysiologic insulin doses are not recommended, because they can result in hypokale- mia, hypophosphatemia, or delayed hypoglycemia Management [21,22]. Standard insulin therapy for DKA uses an The clinical management of diabetic hyperglyce- IV bolus of 0.15 U/kg of regular insulin, followed by mic crises is complex, and requires frequent attention a continuous insulin infusion of 0.1 U/kg/hour [18]. to details regarding hydration, electrolyte repletion, Smaller insulin doses may be used for treating HHS. and acid-base status. For this reason, patients who have In some cases of HHS, insulin may not be required to DKA or HHS are best managed in an ICU setting. The lower BG levels, because tissue perfusion and insulin initial goals of therapy for both syndromes are to sensitivity may be restored by volume restoration replace volume and electrolyte deficits. Hyperglyce- alone. Ideally, BG levels should decrease by 50 to mia should be corrected slowly. A modification of the 75 mg/dL/hour [18]. To achieve this steady decline, ADA-endorsed treatment algorithm for DKA/HHS it is essential to monitor BG hourly during the early [18] is presented in Fig. 2. The five major components hours of therapy. After BG is less than 250 mg/dL of therapy are considered below. (and ketoacids have been cleared, in DKA), subcuta- neous (SQ) insulin therapy can be initiated. In Volume replacement. Restoration of intravascular patients who have DKA, it is best to overlap IV and volume is the first goal of therapy, to correct tissue SQ insulin therapy by 1 to 2 hours, to prevent recur- hypoperfusion, improve glomerular filtration (restor- rent ketonemia. Following the restoration of normo- ing renal glucose and ketone clearance), and reverse glycemia, long-term diabetes management may be insulin resistance. DKA and HHS may present with slowly (re)initiated. massive total-body water deficits, up to 10 to 12 L [15,19]. Although water losses generally exceed the Potassium. Aggressive potassium repletion is criti- loss of salts, volume replacement should typically cally important during therapy for DKA or HHS. begin with isotonic saline (0.9% NaCl). Intrave- Hypokalemia can result in weakness, muscle cramps, nous (IV) fluid regimens vary, but it is standard to and nausea. Intracellular potassium depletion may also administer one liter of saline within the first 30 to trigger dangerous cardiac arrhythmias. At the time of 60 minutes, followed by a continuous infusion of 250 presentation, most patients who have DKA/HHS have to 500 mL/hour [20] as guided by clinical and labora- severe total body potassium deficits, on the order of tory parameters. During volume replacement for 3 to 6 mEq/kg. Admission potassium levels may be DKA, after blood glucose (BG) levels have fallen low, normal, or even high, especially in the presence of below 250 mg/dL, dextrose should be added to the acidosis or renal insufficiency [23]. After therapy for IV fluids, to minimize the risks of cerebral edema and DKA/HHS has been initiated, serum potassium levels hypoglycemia during continued IV insulin therapy. In often decrease precipitously, because of an insulin- pediatric patients, hypotonic fluids (eg, 0.45% NaCl) mediated intracellular shift of potassium ions. In ad- should generally be avoided because they can precip- dition, IV saline therapy dilutes circulating potassium 586 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

Fig. 2. (A) Management of adult patients who have diabetic hyperglycemic states. Volume repletion and insulin therapy. (B) Management of adult patients who have diabetic hyperglycemic states. Potassium repletion. *K+ repletion should be started after the initial fluid resuscitation with at least 1000 mL of isotonic saline. (C) Management of adult patients who have diabetic hyperglycemic states. Bicarbonate therapy. P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 587

Fig. 2 (continued).

and stimulates urinary potassium excretion [24]. Hy- bonate should be used with extreme caution because it pokalemia on presentation demands aggressive potas- can precipitate hypokalemia and may impair oxygen sium repletion; in such cases, insulin therapy should be delivery to peripheral tissues. In addition, alkalosis withheld until potassium levels exceed 3.3 mg/dL [25]. may develop as patients recover from ketoacidosis. ‘‘Normal’’ potassium levels should also be supple- In most patients, acid-base status will improve mented early during therapy, in anticipation of thera- with volume restoration and insulin therapy alone. If py-induced potassium shifts [18]. In patients who have bicarbonate is used, it should be administered slowly abnormal potassium levels (high or low), frequent and in small doses. 1 amp (44 mEq) may be given ECG monitoring is recommended throughout the early over 1 hour for pH less than 7.0, whereas 1 to 2 amps phases of therapy. may be used if pH is less than 6.9 [18]. Following the administration of bicarbonate, arterial pH (and serum Phosphate. Like potassium levels, serum phosphate potassium) levels should be monitored at least every levels may be falsely elevated on presentation because 2 hours until pH exceeds 7.0, at which time alkaline of extracellular shifts. Complications of hypophospha- therapy should usually be discontinued. Continuous temia include respiratory and skeletal muscle weak- infusions of bicarbonate-containing IV fluids are ness, impaired cardiac output, and hemolytic anemia rarely required. [26]. Hypophosphatemia may also hamper oxygen While treating DKA or HHS, clinicians should be delivery to peripheral tissues [27]. Although prophy- cognizant of therapy-related complications, including lactic phosphate repletion is usually unnecessary, hypoglycemia, hypokalemia, and hypophosphatemia. prompt recognition and treatment of phosphate deficits Precautions to avoid these common complications are important [28,29]. IV phosphate repletion may were described. Two rare, but potentially fatal, com- be indicated if serum levels decrease to less than plications deserve special mention. Cerebral edema is 1.0 to 1.5 mg/dL, whereas oral repletion is usually associated with overaggressive correction of hyper- adequate for mild hypophosphatemia. To prevent glycemia and hypotonic fluid therapy [32,33]. This hypocalcemia, calcium and magnesium levels should complication, which is more common in the pediatric be carefully monitored in all patients who receive population, is believed to result from osmotically phosphate therapy. driven fluid shifts into the central nervous system (CNS) [34]. Clinically, cerebral edema presents with Bicarbonate. In most patients who have DKA, keto- lethargy, headache, and progressive neurologic dete- acids clear spontaneously with standard therapy, be- rioration. Emergent neurosurgical consultation is rec- cause insulin suppresses lipolysis and ketogenesis, ommended in all cases. The acute respiratory distress whereas the restoration of plasma volume improves syndrome (ARDS), characterized by noncardiogenic renal ketone clearance. For these reasons, the routine pulmonary edema and an increased alveolar-arteriolar use of alkali therapy for DKA is not recommended (see oxygen gradient, has also been attributed to rapid references [18,30,31]). In severe cases (pH < 7.0), reductions in osmotic pressure [35]. Affected patients bicarbonate therapy may be used to stimulate cardiac present with respiratory distress, hypoxia, and radio- inotropy and reverse peripheral vasodilatation. Bicar- graphic evidence of pulmonary edema. Because high 588 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

IV fluid infusion rates are associated with cerebral simply be at increased baseline risk for adverse car- edema and ARDS, fluid administration (and correc- diovascular outcomes. tion of hyperglycemia) must be slowed in patients Until recently, few studies have examined the spe- who have either condition [12]. cific impact of glycemic control on short-term clinical outcomes during intensive care. In the mid-1990’s, Hyperglycemia and intensive insulin therapy in the diabetes mellitus insulin-glucose infusion in acute critically ill patients myocardial infarction (DIGAMI) study [52,53] showed that the use of an inpatient insulin-glucose Stress hyperglycemia (used herein to denote stress- infusion (followed by an intensive outpatient insulin induced elevations in [BG] and free fatty acid [FFA] regimen) reduced mortality in diabetic patients follow- levels) occurs in most critically ill patients [36,37]. ing acute MI. The DIGAMI study examined predom- Severe stress or critical illness induces several altera- inantly long-term outcomes, however, and was not tions in carbohydrate and fatty acid metabolism, in- truly a study of intensive inpatient insulin therapy. In cluding increased hepatic gluconeogenesis, peripheral 1999, Furnary et al [54] reported reductions in deep insulin resistance, and the liberation of FFAs from sternal wound infections following the introduction of adipose stores [37]. In a variety of clinical settings, intensive BG control; however, this was a retrospec- stress hyperglycemia was associated with adverse tive study and was limited by the use of historical clinical outcomes. After myocardial infarction (MI), controls. In 2000, Lazar et al [55] published a pro- for example, hyperglycemia predicts increased rates of spective, randomized, controlled trial of 40 diabetic congestive heart failure, cardiogenic shock, and death patients who were undergoing coronary surgery, and [38,39], whereas high FFA levels have been associated reported that glucose-insulin-potassium infusions with excess cardiac arrhythmias and mortality [40,41]. (which lowered BG levels) improved cardiac index, Following acute stroke, stress hyperglycemia also was shortened duration of ventilatory support, and short- associated with increased mortality and with dimin- ened hospital stay. This study, although convincing, ished neurologic recovery [42]. In patients who were was not powered to detect significant differences in admitted to an ICU, impaired glucose and lipid me- many other important clinical outcomes. tabolism is associated with increased severity of illness In 2001, Van den Berghe et al [56] published a and decreased survival [43]. large, prospective, randomized controlled trial of in- Several pathophysiologic mechanisms have been tensive BG control in 1548 patients admitted to a proposed to explain the relationship between stress surgical ICU in Leuven, Belgium. The status of two hyperglycemia and adverse clinical outcomes. First, thirds of the patients that were enrolled in this study stress hyperglycemia occurs in the setting of peripheral was postcardiac surgery. Upon admission, patients insulin resistance [37]. Such conditions limit the abi- were randomized to either ‘‘conventional’’ (IV insulin lity of tissues to use metabolic fuels and permit the drip if BG>215 mg/dL, target BG = 180–200 mg/dL) local accumulation of FFAs, which can damage cell or ‘‘intensive’’ (IV insulin drip if BG>110 mg/dL, membranes and impair tissue performance (see refer- target BG = 80–110 mg/dL) insulin therapy. Intensive ences [37,41,44]). Hyperglycemia may also precipitate therapy reduced ICU mortality by 42%, and dramati- an osmotic diuresis, which reduces vascular volume cally reduced the risk for several other morbid clinical and results in decreased cardiac output and impaired outcomes, including prolonged ICU stay, prolonged tissue perfusion [45]. Hyperglycemia also has been need for ventilatory support, need for dialysis, septi- associated with several immune system abnormalities, cemia, and critical illness polyneuropathy (Fig. 3). The including impaired leukocyte chemotaxis [46], im- mortality benefits seen in the Leuven study applied paired phagocytosis [47,48], and decreased immuno- exclusively to patients who remained in the ICU for globulin function and complement fixation [49]. more than 5 days, and primarily reflected a reduction in Stress hyperglycemia typically occurs in the setting deaths from multiple-organ failure with sepsis, regard- of excess glucagon, cortisol, and catecholamine re- less of pre-existing diabetes [56,57]. The Leuven study lease [50]. Any or all of these counter-regulatory strongly supports the implementation of intensive BG hormones may contribute to adverse clinical outcomes control in cardiothoracic ICUs. Because the benefits during critical illness. Finally, stress hyperglycemia obtained seemed to be mediated by reduced infectious may simply be a marker for previously undiagnosed complications, these benefits should apply to patients impaired glucose tolerance or diabetes; patients who who are admitted to other types of ICUs, as well. have either condition are known to have an increased Whether the Leuven study results can be generalized to prevalence of cardiovascular disease [51]. Thus, pa- other ICU populations (eg, medical ICU patients) tients who exhibit hyperglycemia during stress may remains to be established, however. P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 589

Fig. 3. Relative risk reductions for key measures of ICU morbidity in the Leuven study. *P<0.01, yP<0.0001. Error bars: 95% confidence intervals. Adapted from Van den Berghe G. Beyond diabetes: saving lives with insulin in the ICU. Int J Obesity 2002;26(Suppl 3):S6; with permission.

Based on the available data, we strongly endorse thostatic hypotension may suggest the diagnosis. the standardized implementation of intensive infusion Clinically, primary adrenal insufficiency may present protocols in critically ill patients. Patients who have a with hyperpigmentation (due to excess corticotropin history of diabetes should be targeted for intensive [ACTH] production), hyponatremia, or hyperkalemia therapy. In addition, four common ICU interventions (due to mineralocorticoid [MC] deficiency). If present, — corticosteroids, vasopressors, enteral nutrition, and adrenalitis may be found in association with other parenteral nutrition — also predispose to poor BG autoimmune diseases, including vitiligo, thyroiditis, control in the ICU [58]. Patients who receive any of and type 1 diabetes [61]. Secondary adrenal insuffi- these four interventions should be monitored as fre- ciency, due to hypothalamic-pituitary disease, may quently as patients who have known diabetes for the be associated with headaches, visual symptoms, or presence of hyperglycemia, and should be treated as other pituitary hormone deficiencies, including hypo- aggressively. In terms of achieving tight BG control, thyroidism, hypogonadism, growth hormone defi- we recognize that levels of 80 to 110 mg/dL are ciency, or diabetes insipidus [61]. difficult to achieve practically and safely in most Acute adrenal insufficiency, unlike the chronic current ICUs (mostly because of staffing issues). For disease, presents with rapid, dramatic clinical deterio- this reason, we currently endorse more conservative ration, with cardinal signs including fever, abdominal target BG levels of 100 to 139 mg/dL, which can be pain, neuropsychiatric manifestations, and hemody- safely and reliably achieved using a standard insulin namic instability [62]. Addisonian crises may occur in infusion protocol [59]. These intensive protocols can patients who have chronic adrenal insufficiency in be implemented (and readily accepted) by a busy ICU whom steroid therapy is interrupted, or in the setting nursing staff without the need for subspecialty consul- of superimposed stress or illness. Acute decompensa- tation. In the future, we predict that the development of tion may also occur in the setting of sudden adrenal continuous glucose monitoring strategies in the ICU injury, most often as a result of hemorrhage, infection, [60] will promote tighter BG control. Ultimately, such or inflammation [63]. Pituitary injury can also lead to advances would likely contribute to improved patient adrenal insufficiency; in this situation, however, the outcomes during ICU care. clinical presentation is usually less severe and hyper- kalemia is absent because of intact MC secretion from the adrenal glands. An extensive differential diagnosis Critical issues in adrenal disease for adrenal insufficiency (acute and chronic forms) is provided in Box 1. Acute adrenal insufficiency: Addisonian crisis Diagnosis Clinical presentation Laboratory evaluation for chronic adrenal insuffi- When present as a chronic condition, adrenal in- ciency is a complex and controversial issue and is re- sufficiency can be difficult to diagnose. Nonspecific viewed elsewhere [61,64]. If Addisonian crisis is historical features, including chronic fatigue, depres- suspected, an emergent ‘‘stress’’ cortisol level should sion, weakness, anorexia, nausea, diarrhea, or or- be obtained, followed by empiric coverage with 590 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

Familial GC deficiency Box 1. Differential diagnosis for adrenal Adrenoleukodystrophy insufficiency Adrenomyeloneuropathy Drugs Primary adrenal insufficiency Etomidate, ketoconazole, Hemorrhage metyrapone, aminoglutetha- Waterhouse-Friderichsen mide, mitotane (inhibited syndrome (Septicemia, DIC) steroid synthesis) Idiopathic thrombocytopenic Phenytoin, phenobarbital, purpura rifampin (increased steroid Thrombotic thrombocytopenic catabolism) purpura Hypothermia Heparin-inducedthrombocy- Secondary adrenal insufficiency topenia Exogenous corticosteroid therapy Antiphospholipid antibody Hypothalamic/pituitary disease: syndrome Tumor: craniopharyngioma, Systemic lupus erythematosus pituitary adenoma/carcinoma Anticoagulation (Heparin, Infiltrative diseases: hemochro- Warfarin) matosis, sarcoidosis, amyloi- Infections dosis, histiocytosis Mycobacterium tuberculosis Autoimmune: lymphocytic (HIV)-related infections hypophysitis Primary HIV infection Hemorrhage: pituitary apoplexy Cytomegalovirus Postpartum pituitary necrosis Mycobacterium avium (Sheehan’s syndrome) intracellulare Postsurgical hypopituitarism Cryptococcus neoformans Posttraumatic hypopituitarism Toxoplasmosis gondii Postradiation hypopituitarism Kaposi’s sarcoma ‘‘Empty sella syndrome’’ Fungal infections Isolated ACTH deficiency Histoplasma capsulatum Blastomyces dermatiditis Coccidioides immitis Metastases Solid tumors: lung, breast, gastric ‘‘stress-dose’’ steroids (see later discussion) until the Malignant melanoma results have returned. For years, ‘‘conventional wis- Lymphoma dom’’ has held that ‘‘normal’’ cortisol responses to Autoimmune stress exceed 20 mg/dL. This historical threshold was (Isolated) autoimmune adrenalitis based primarily on responses in healthy patients, Polyglandular autoimmune however, to either supraphysiologic doses (250 mg) syndrome type 1 of corticotropin or insulin-induced hypoglycemia Adrenalitis, hypoparathyroid- [65,66]. More recently, 25 mg/dL has been advocated ism, mucocutaneous as an ‘‘adequate’’ cortisol response to stress [67]. This candidiasis new threshold was proposed based on observations Polyglandular autoimmune that during critical illness, mean cortisol values gen- syndrome type 2 (Schmidt’s erally exceed 45 mg/dL [68–70], whereas fewer than syndrome) 10% of patients mount a cortisol response that is less Adrenalitis, thyroiditis, type 1 than 25 mg/dL [66]. At the present time, controversy diabetes mellitus surrounds the definition of a ‘‘normal’’ cortisol re- Genetic sponse to stress and the proper use of adrenocortical Congenital adrenal hyperplasia diagnostic testing during critical illness [71]. (classic) The ‘‘high-dose’’ (250 mg) corticotropin stimula- Congenital adrenal hypoplasia tion test (CST) is most commonly used to diagnose adrenal insufficiency in the ICU [64,65]. This test P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 591 raises circulating ACTH levels to 60,000 pg/mL, hypoglycemia. During the initial phase of therapy, which is far higher than the 100 pg/mL concentrations aggressive hemodynamic or respiratory support may that are required to maximally stimulate the adrenal be required. Emergent treatment of severe electrolyte cortex under basal conditions [72]. For this reason, the abnormalities (hypokalemia, hyponatremia) may be high-dose test may lack sensitivity [73,74]. The ‘‘low- indicated as well. dose’’ (1 mg) CST more closely approximates physio- If chronic GC replacement therapy is required, logic hypothalamic-pituitary-adrenal (HPA) responses typical oral regimens include hydrocortisone, 20 to to stress, and is preferred by some investigators for 30 mg/day or prednisone, 5 to 7.5 mg/ day, usually in outpatient evaluations of the adrenal axis, especially divided doses. Dose adjustments for GC replacement when pituitary disease is suspected [75–77]. In select are symptom-guided. For primary adrenal insuffi- patients who have critical illness, the low-dose CST ciency, chronic MC replacement may be required, may offer superior sensitivity [78] and was advocated usually provided as oral fludrocortisone in doses of by some investigators [63,79]. Overall experience with 50 to 200 mg/day. MC dosing should be guided by the low-dose CST in patients in the ICU is lacking. measurements of blood pressure, sodium, and potas- Because critical illness may be associated with adrenal sium. Plasma renin activity, which should be main- resistance to ACTH [71,80] or target tissue resistance tained in, or slightly above, the high-normal range, to steroid activity [81], the use of the low-dose CST in may be helpful in certain cases. Occasionally, patients this setting cannot be fully endorsed at the present who are taking hydrocortisone may do well without time. At our institution, we recommend a high-dose specific MC therapy, because hydrocortisone has some CST as first-line testing for adrenal insufficiency in intrinsic MC activity. With prednisone and other pure critically ill patients. In the setting of severe illness, GCs, specific MC replacement is nearly always re- ‘‘random’’ cortisol levels that are less than 20 to quired for primary hypoadrenalism. 25 mg/dL may adequately establish the diagnosis. In outpatients, the HPA axis may be assessed using Chronic adrenal insufficiency: ‘‘stress dosing’’ of the insulin tolerance test [64], the overnight me- steroids during critical illness tyrapone test [82], or stimulation with corticotropin releasing hormone (CRH) [64,83].Duringcritical In patients who have a history of chronic adrenal illness, insulin-induced hypoglycemia and metyra- insufficiency (including patients on long-term steroid pone testing pose undue risk and should not be therapy), GC supplementation is recommended during performed. The CRH test has not been validated in times of significant stress, including surgery and patients in the ICU, although it may be useful in dis- critical illness. Precise recommendations for peri- tinguishing hypothalamic from pituitary disease [84]. operative GC coverage have been hampered by a lack In the setting of Addisonian crisis, after the laboratory of prospective studies. Recent publications suggested diagnosis has been established, CT imaging should that even major surgery may not significantly increase be used to examine the adrenal glands. If the clinical GC requirements [85,86]. In a 1994 surgical consensus picture suggests secondary adrenal insufficiency article [87], recommendations for hydrocortisone were (ie, lack of hyperkalemia, known pituitary hormone 25 mg/day (or its equivalent) during minor surgery deficiencies, visual field deficits), an MRI of the sella (eg, laparoscopic surgery), 50 to 75 mg/day during turcica should be obtained. In the presence of adrenal moderate surgery (eg, hysterectomy), and 100 to hemorrhage, a hematocrit, platelet count, coagulation 150 mg/day during major surgery, including cardio- studies, and additional specific diagnostic tests pulmonary bypass and major abdominal operations. (eg, antiphospholipid antibody, lupus anticoagulant) Postoperatively, ‘‘stress’’ doses are recommended for may be useful in establishing the underlying diagnosis. only 1 to 3 days in the absence of complications or nonsurgical illness [87]. Treatment Similar guidelines could be reasonably applied to Therapy for acute adrenal insufficiency consists patients in a medical ICU, with ‘‘stress-dose’’ GC of ‘‘stress-dose’’ GC therapy, typically given as hy- coverage ( 150 mg/day hydrocortisone or equiva- drocortisone 100 mg IV every 6 to 8 hours (or its lent) throughout the critical phase of illness. ‘‘Maxi- equivalent). MC therapy should be considered if mal’’ GC doses (300–400 mg/day hydrocortisone or primary hypoadrenalism is suspected, but is not re- equivalent) may be preferable in patients who have quired for hypothalamic-pituitary disease. Patients pressor-resistant hypotension, or in other clinical sit- who have hypotension should receive aggressive vol- uations (eg, septic shock, see later discussion) where ume repletion; in general, dextrose should be added to ACTH or GC resistance is suspected [88]. Following all IV fluids, because of a high incidence of associated the resolution of critical illness or following recovery 592 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 from surgery, tapering of steroid doses is generally In critically ill patients, extreme cortisol levels (low recommended. One reasonable approach is to drop GC and high) have been associated with increased severity doses by 25% to 50% per day until maintenance doses of illness and increased mortality [93,94]. Presumably, are resumed. Slower tapers may be preferred in low cortisol levels indicate adrenal insufficiency, patients who have a history of more severe or pro- whereas high levels are associated with increased longed illness. severity of illness. Impaired adrenal responses to ACTH have also been linked to increased mortality Relative adrenal insufficiency in septic shock [95]. In 2000, Annane et al [96] tested the high-dose CST in patients who had septic shock as a means of In recent years, there has been renewed interest determining prognosis. Patients who had baseline in using corticosteroid therapy for the treatment of cortisol levels that were 34 mg/dL or less and an intact patients who have septic shock. Corticosteroids are cortisol response during the high-dose CST (>9 mg/dL) essential in maintaining normal metabolic, hemody- had the best clinical outcomes, with a 28-day mortality namic, and immune function. During times of severe rate of only 26%. Patients who had high baseline stress (eg, septic shock), the HPA axis should be maxi- cortisol levels (>34 mg/dL) and a blunted CST re- mally stimulated. Multiple factors may contribute to sponse (V9 mg/dL) fared the worst, with a 28-day ‘‘relative’’ hypoadrenalism during septic shock, how- mortality rate of 82% (Fig. 4). For any given baseline ever, including adrenal injury (eg, infection, hemor- cortisol level, blunted CST responses (V9 mg/dL) rhage), hypoperfusion, or the use of centrally active imparted a poor prognosis [96]. These results lend pharmacologic agents, such as opiates and sedatives support to the routine use of the high-dose CST in [67]. Adrenocortical responses to ACTH are often patients who have septic shock, to provide prognostic blunted in critically ill patients [71,80]. This phenom- information and to guide adjunctive steroid therapy. enon may be partially explained by near-maximal These data have an alternate interpretation, how- stimulation of the adrenal cortex during stress, but ever; patients who had the most severe illness (and, may also reflect reduced adrenal cortisol production or therefore, the poorest prognosis) may simply have reduced adrenal sensitivity to ACTH [80].Inthe maximized their steroid output, which resulted in a setting of septic shock, cytokines and other inflamma- ‘‘failed’’ CST. tory mediators suppress the HPA axis [89–91]. Evi- Because relative adrenal insufficiency is common dence for reversible adrenal failure during septic shock in patients who have septic shock, and because blunted comes from Briegel et al [92], who performed high- adrenal responses to a high-dose CST confer a poor dose CSTs in 20 patients who had septic shock, prognosis, an obvious question arises: Does steroid during acute illness and following recovery. Defining supplementation improve outcomes in patients who 25 mg/dL as an ‘‘adequate’’ cortisol response, 13 of the have septic shock? Earlier studies that examined the 20 patients demonstrated relative adrenal insufficiency use of steroids in septic shock showed no survival in the ICU. Following recovery, CST responses benefit [97–100]. These studies used short-term, returned to normal in most patients. supraphysiologic steroid doses in unselected ICU

Fig. 4. Survival curves of patients who are admitted to the ICU with septic shock, when considered by basal plasma cortisol levels and the maximum response to a 250-mg corticotropin stimulation test. (From Annane D, Sebile V, Troche G, Raphael JC, Gajdos P, Bellissant E. A three-level prognostic classification in septic shock based on cortisol levels and cortisol response to corticotrophin. JAMA 2000;283:1044; with permission.) P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 593 populations, however. More recent studies, that in- specific MC therapy (ie, fludrocortisone) seems un- voked the concept of ‘‘relative adrenal insufficiency’’ warranted and could contribute to fluid overload, (ie, pressor-dependent hyperdynamic shock) demon- congestive heart failure, or hypokalemia. Current evi- strated beneficial clinical effects of steroid therapy dence suggests little risk from the use of low-dose MC during septic shock, including reduced need for vaso- therapy in patients in the ICU, however [107]. pressors, faster weaning from mechanical ventilation, If a patient ‘‘passes’’ the CST test on admission, and improved survival [101–104]. GCs are required longitudinal testing should be considered (on a case- for proper functioning of adrenergic receptors. Al- by-case basis) because HPA activation may decline as though sepsis impairs adrenergic responses [101], critical illness progresses [110]. This decline may be steroid therapy seems to restore adrenergic tone, thus driven by a change in hypothalamic-pituitary sensi- restoring hemodynamic responsiveness to adrenergic tivity to circulating GCs or by a change in adrenal stimuli [105,106]. sensitivity to ACTH stimulation [71]. Finally, in all In 2002, Annane et al [107] published a large, patients who have documented adrenal insufficiency placebo-controlled, randomized, double-blind, multi- in the ICU, repeat testing is recommended following center trial that was performed in 300 patients who had the resolution of critical illness, to exclude chronic septic shock. In this study, treatment with hydrocorti- adrenal insufficiency. sone (50 mg, IV every 6 hours) and fludrocortisone (50 mg/d po) reduced mortality in patients with septic shock by 16%. The benefits were restricted to patients Critical issues in thyroid disease who had ‘‘relative’’ adrenal insufficiency, which was defined as a cortisol response 9 mg/dL or less to a high- Thyroid function tests in the ICU: the ‘‘nonthyroidal dose (250 mg) CST. In this study, ‘‘nonresponders’’ illness syndrome’’ (CSTresponse V 9 mg/dL) had an average baseline cor- tisol level of 21 mg/dL (mean CST response 1 mg/dL), The interpretation of thyroid function tests (TFTs) whereas responders had a mean level of 30 mg/dL in the ICU can be difficult because thyroid hormone (mean CST response 22 mg/dL). This suggested that (TH) concentrations are affected by a wide variety of higher baseline cortisol levels were associated with nonthyroidal stresses, including sepsis [111,112], more vigorous CST results. Although these investi- HIV/AIDS [113,114], malignancy [115,116], myocar- gators’ definition of relative adrenal insufficiency and dial infarction [117], major surgery [118,119], and their choice of treatment doses can be questioned, it severe malnutrition [120,121]. In addition, common seems clear that the use of steroids in the setting of ICU medications, including dopamine [122], cortico- relative adrenal insufficiency conferred clinical bene- steroids [123], amiodarone [124], and iodinated radio- fit. Based on this and other studies [108], we believe contrast agents can also affect thyroid physiology. In that screening for relative adrenal insufficiency is the ICU, clinicians frequently encounter the ‘‘sick warranted in patients in the ICU who have septic euthyroid syndrome’’ [125] or ‘‘nonthyroidal illness shock. The optimal means of diagnosis and treatment syndrome’’ (NTIS) [126] which is characterized by remain to be established. low TH levels in the setting of systemic illness. Based on the available data, we recommend obtain- Because patients in the ICU are usually catabolic, it ing a screening ‘‘stressed’’ cortisol level in all patients was suggested that the low TH concentrations that are who have septic shock upon admission. Because observed during nonthyroidal illness (NTI) are a critically ill patients lose their diurnal variation in physiologic response to stress and serve to decrease cortisol production [94,109], morning cortisol levels unnecessary energy expenditure [127]. Because the are not required and may delay the diagnosis. A magnitude of the TH disturbance is associated with ‘‘stressed’’ cortisol level of less than 20 mg/dL suggests disease severity [117] and mortality [128,129], how- relative hypoadrenalism and physiologic steroid ever, the NTIS also may represent a maladaptive therapy should be considered (see later discussion). response that threatens tissue function. If cortisol levels exceed 20 mg/dL, a high-dose CST Critical illness can induce many abnormalities should be performed; nonresponders (cortisol re- of the hypothalamic-pituitary-thyroid axis, including sponse V 9 mg/dL) should also be considered candi- diminished thyrotropin (TSH) release, reduced levels dates for steroid therapy unless baseline levels exceed of tri-iodothyronine (T3) or thyroxine (T4), reduced 34 mg/dL [108]. In the ICU setting, hydrocortisone is thyroid binding globulin (TBG) levels, and peripheral the preferred GC because it possesses some intrinsic TH resistance. Although NTI can produce a wide MC activity. Because patients who have septic shock variety of TFT abnormalities, most patients fall into a are usually receiving continuous IV fluids, the use of ‘‘continuum’’ of three NTI syndromes: (1) low T3, 594 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

(2) low T3 and low T4, and (3) low T3, low T4, and the T3/T4 deficit correlates with illness severity and low TSH. The classic biochemical progression of TFT poor clinical prognosis [128]. abnormalities during NTI is shown in Fig. 5. Low T3, low T4, and low TSH syndrome Low T3 syndrome Although TSH elevations have been reported with The low T3 syndrome is the most common form of NTIS [132], most affected patients have TSH levels NTIS and occurs in up to 70% of hospitalized patients that are in the normal or low-normal range. Patients [126]. During severe illness, T3 levels usually de- who have more severe illness (or patients who receive crease within 24 hours [130] because of reduced dopamine or corticosteroids) may have low or even extrathyroidal conversion of T4 to T3 (ie, decreased undetectable TSH levels. The finding of low TSH with 5V-deiodinase activity) and increased production of low T3/T4 suggests an altered hypothalamic-pituitary reverse T3. GCs, amiodarone, and iodinated radio- response to TH [133]. During recovery from critical contrast agents may also contribute to reduced periph- illness, elevated TSH levels may be seen [134], which eral TH conversion. In the low T3 syndrome, levels of likely reflect the restoration of the normal hypotha- TSH, total T4, and free T4 are usually normal, lamic-pituitary response to low TH levels. Such TSH although transient elevations in free T4 may be seen elevations are typically modest. TSH levels that ex- (see Fig. 5). In the low T3 syndrome, the magnitude of ceed 20 mU/L suggest primary hypothyroidism. TH deficit has been associated with illness severity Diagnosing NTIS can be challenging. When thy- [118] and mortality following ICU admission [129]. roid function is examined in the ICU, we recommend obtaining a complete thyroid panel, including levels of Low T3 and low T4 syndrome total T4, free T4 (or a calculated free thyroxine index), In patients who have more severe or more pro- total T3, and TSH. During critical illness, the presence longed systemic illness, total T4 levels may decrease, of low T3 or low T4 levels with a normal or low TSH is as well. Although less common than isolated T3 strongly suggestive of NTI; however, true hypothy- deficiency, the ‘‘low T3-T4 syndrome’’ occurs in up roidism can produce similar TFT results. TSH levels to 50% of patients who are admitted to ICUs. Despite may be high, normal, or low in the setting of NTI. If depressed total T4 levels, free T4 levels are usually TSH at least 20 mU/L, primary hypothyroidism is normal (or may be elevated) in this setting; however, likely. If TSH is normal or only mildly elevated free T4 levels may also be depressed in patients who (< 20 mU/L), the presence of low free T4 levels, a thy- are treated with dopamine or corticosteroids. Proposed roid goiter, or antithyroid antibodies suggest primary mechanisms for the low T3 and low T4 syndrome hypothyroidism. Finally, if TSH levels are low, ante- include decreased TH production, TBG deficiency, rior pituitary hormone status should be further as- circulating inhibitors of TH binding (eg, free fatty sessed. Low (or low-normal) cortisol levels and acids), and altered TH metabolism [126]. Cytokines, abnormalities in prolactin secretion suggest pituitary including interleukin (IL)-1, IL-6, and tumor necrosis dysfunction. It should be remembered that transient factor-a, may also be involved in the pathogenesis hypogonadotropic hypogonadism is extraordinarily [131]. As with the low T3 syndrome, the magnitude of common in critically ill patients. Therefore, assess-

Fig. 5. Thyroid function tests in the nonthyroidal illness syndrome. P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 595 ment of the gonadal axis is usually not helpful in this skin and soft tissue swelling, often with associated setting. Unfortunately, the measurement of reverse T3 periorbital edema, ptosis, macroglossia, or cool, dry is not helpful in clarifying thyroid status [135].Asa skin. Additional clinical features of myxedema coma general rule, establishing the diagnosis of the NTIS are summarized in Table 3. based on a single day’s TFTs is not advisable. Most The diagnosis of myxedema coma requires confir- often, repeat TFT interpretation in the setting of an mation with low (or undetectable) levels of T4 (total evolving clinical course is required to firmly establish and free) and T3. TSH levels are usually elevated, but the diagnosis. may be normal (or even low) in the setting of hypo- Because NTIS is associated with increased mortal- thalamic-pituitary disease or advanced critical illness ity, it is important to establish whether TH replacement (eg, NTIS). Additional laboratory findings include nor- improves outcomes in critically ill patients. Studies mocytic anemia, hyponatremia, hypoglycemia, azote- that examined this question have yielded conflicting mia, and elevated creatine kinase levels. Hypoxia, results. In patients who were undergoing coronary by- hypercapnia, and respiratory acidosis are common pass procedures, T3 improved cardiac output [136] findings on arterial blood gas analysis. and may reduce mortality [137]. In contrast, other The treatment of myxedema coma involves general studies in patients who were undergoing coronary supportive measures, correction of physiologic de- bypass [138] and in medical ICU patients [139] failed rangements, and immediate intravenous replacement to show clinical benefit with T3 therapy. In light of the of TH. Patients should be treated in an ICU setting, disparate evidence and considering that intracellular with intensive cardiac, hemodynamic, and blood glu- hypothyroidism may be protective during critical ill- cose monitoring. Mechanical ventilation may be re- ness, TH therapy is not currently recommended for quired. In patients who have severe hypotension, most patients who have NTIS. If primary hypo- vasopressor therapy should be considered, although thyroidism is suspected in the ICU, TH therapy should pressors should generally be avoided in borderline be initiated, with the immediate goal of increasing TH cases because they can exacerbate cardiac arrhyth- levels into the normal range. If secondary hypothy- mias. To correct hypothermia, a warm room tempera- roidism is suspected, ‘‘stress-dose’’ steroid therapy ture and blankets should be used in most cases because should accompany TH replacement until adrenal in- rapid rewarming, and its associated peripheral dilata- sufficiency can be definitively ruled out. tion, may precipitate hypotension and cardiovascular collapse. Ultimately, normal thermoregulation should Critical hypothyroidism: ‘‘myxedema coma’’ be rapidly restored by the administration of thyroid hormone. If present, severe hyponatremia may be The term ‘‘myxedema coma’’ often is used to treated with hypertonic saline, with or without loop describe clinically severe hypothyroidism. This term diuretics. Hypoglycemia should be treated with a is often a misnomer, however, because most patients continuous intravenous dextrose infusion, with fre- who have severe hypothyroidism present with neither quent attention to sodium levels if hypotonic solutions myxedema nor a comatose state. Instead, critical hypo- thyroidism is characterized by progressive dysfunction Table 3 of the cardiovascular, respiratory, and CNS. If not Clinical manifestations of myxedema coma rapidly recognized and treated, the mortality rate that is associated with this condition is exceedingly high. Organ system Clinical features Myxedema coma occurs most commonly during Skin and soft tissue Generalized swelling; edema; the winter months, when thermoregulatory stressors periorbital edema; ptosis; cool, are at maximum levels. Common precipitants include dry skin; Coarse, sparse hair; hypothermia, trauma, burns, surgery, stroke, sepsis, Macroglossia; hoarseness Neurologic Hypothermia, Lethargy, altered and severe infections. Medications, including anes- mental status, Psychosis, Seizures, thetics, sedatives, narcotics, diuretics, and b-blockers Delayed reflex relaxation have also been implicated [140]. Typically, patients are Cardiovascular Bradycardia, hypotension older and have known hypothyroidism; however, Respiratory Depressed ventilatory drive, hypo- myxedema coma can be the initial presentation of ventilation, hypoxia, hypercapnea hypothyroidism. Cardinal findings include defective Gastrointestinal Constipation, abdominal distention thermoregulation (hypothermia) and altered mental paralytic ileus, megacolon status; additional clinical features include bradycardia, Hematologic Anemia blunted stress leukocytosis hypotension, hypoventilation, and hyponatremia. If Renal and Electrolyte Hyponatremia decreased glomeru- present, ‘‘myxedema’’ is characterized by generalized lar filtration rate 596 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 are used. Finally, precipitating factors should be ac- Box 2. Therapy for myxedema coma tively pursued. If no obvious precipitants are identi- fied, broad-spectrum antibiotic therapy should be Initiate supportive therapy considered until infection has been ruled out, because severe hypothyroidism can blunt the normal leukocyte Hypoventilation: oxygen therapy, response to infection. mechanical ventilation The proper initiation of TH therapy during myx- Hypotension: saline therapy, blood edema coma is controversial, particularly with regards transfusions (if severe anemia) to the selection and dosing of TH used. In vivo, T3 is Avoid vasopressors if possible the active hormone; circulating T4 is converted to T3 (may worsen risk for arrhythmia) by peripheral deiodinase activity. Because deiodinase Hypothermia: passive rewarming activity is suppressed during severe hypothyroidism (warm room, simple blankets) [125], some investigators advocate intravenous T3 Avoid active rewarming if possible replacement therapy [141], which offers a more rapid (may precipitate vascular onset of action. Parenteral T3 is expensive and difficult collapse) to obtain, however, and may be associated with cardiac Hyponatremia: saline, free arrhythmias and increased mortality [142].Atour water restriction institution, the routine use of intravenous T3 is not If severe, consider hypertonic generally recommended. saline F diuresis Most investigators recommend initiating therapy Hypoglycemia: intravenous with intravenous T4 alone [143,144], with loading dextrose infusion (D5NS) doses of 200 to 500 mg followed by 50 to 100 mg/day. Higher loading doses do not seem to offer additional Thyroid hormone replacement benefit [145]. If combination T3/T4 therapy is used, loading doses of approximately 4 mg/kg of T4 and Initial replacement: Levothyroxine 10 mg of T3 may be used, followed by maintenance (T4): 200 to 500 Mg, IV doses of T4 (50–100 mg daily) and T3 (10 mg, every Consider concurrent Liothyronine 8 hours) until pills are initiated [140]. Whatever the (T3): 10 Mg, IV regimen, subsequent TH dosing should be guided by Follow-up replacement (until able the frequent measurement of free T4 and TSH levels. to take po): T4 50 to 100 Mg, Along with TH, most investigators recommend the IV, every day concurrent administration of ‘‘stress-dose’’ corticoste- Consider concurrent T3 replace- roid therapy for myxedema coma (see references ment: 10 Mg, IV, every 8 hours [140,143,144]), in case of concurrent adrenal insuffi- ciency as might be seen in hypopituitarism or poly- Corticosteroid therapy glandular autoimmune disease. Hydrocortisone, 50 to 100 mg (or its equivalent), IV, should be administered Draw baseline cortisol level every 6 to 8 hours. Support for this practice is provided Give hydrocortisone, 100 mg, IV by the observation that cortisol responses to stress are (or equivalent) every 6 to 8 hours blunted during severe hypothyroidism [145]. Cortisol Follow-up steroid therapy: levels should be drawn before therapy is initiated; if If initial cortisol level at least appropriately elevated (>25 mg/dL), corticosteroid 25 Mg/dL, consider discontinu- therapy may be safely discontinued. If cortisol is either ing low or suboptimally elevated (< 25 mg/dL), steroid steroid therapy therapy should be continued until the critical phase If initial cortisol level is less than of illness has resolved. At a later time, corticotropin 25 Mg/dL, continue steroid stimulation testing can be performed to sort out cases therapy and perform of true hypoadrenalism. Guidelines for the treatment of corticotropin stimulation testing myxedema coma are summarized in Box 2. after critical illness has resolved During treatment for myxedema coma, hemody- namic parameters typically improve within 24 hours, whereas normal thermoregulation is restored within 2 to 3 days. Initial body temperatures that are below 93F or which do not respond to therapy within 3 days P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 597 are associated with a poor prognosis [142]. Additional Table 4 factors that are associated with poor prognosis include Clinical manifestations of thyroid storm advanced age, bradycardia, hypotension, and cardiac Organ system Clinical features complications, including myocardial infarction and Skin and soft tissue Lid lag; proptosis (Graves’ congestive heart failure [142,146]. With advances in disease); warm, moist skin; intensive therapy, the overall mortality rate seems to hyperhydrosis have decreased to less than 20% [146]. Neurologic Hyperthermia, lethargy, altered mental status, psychosis, seizures, Critical hyperthyroidism: ‘‘thyroid storm’’ hyperkinesis, hyperreflexia Cardiovascular Tachycardia, arrhythmia (eg, atrial The term ‘‘thyrotoxicosis’’ is often used to describe fibrillation), systolic hypertension, the hypermetabolic state that results from elevated wide pulse pressure, high-output congestive heart failure circulating levels of TH. Thyrotoxicosis may present Respiratory Dyspnea, tachypnea with a variety of hyperadrenergic clinical manifesta- Gastrointestinal Abdominal pain, nausea, tions, including hyperactivity, nervousness, tremor, vomiting, diarrhea heat intolerance, palpitations, and unexplained weight loss. Diagnostic considerations in patients who have thyrotoxicosis are listed in Box 3. TS most commonly sis and intervention is crucial to prevent morbidity occurs in Graves’ disease, which is associated with the and mortality. highest TH levels. The progression of thyrotoxicosis Many cases of TS are associated with a precipitat- into life-threatening ‘‘thyroid storm’’ (TS) involves ing thyroid event, including thyroid surgery, with- severe thermoregulatory dysfunction (high fever), drawal of antithyroid drugs, radioiodine therapy, or mental status changes, and evidence of multi-organ the administration of iodinated radiocontrast dyes. In dysfunction, including adrenergic crisis (tachycardia, patients who have pre-existing thyrotoxicosis, TS can hypertension) and gastrointestinal hypermotility. Sev- also be precipitated by systemic insults, including eral different diagnostic criteria for TS have been surgery, trauma, parturition, stroke, MI, diabetic keto- proposed [147–149]. An ‘‘apathetic’’ form of critical acidosis, or severe infections. Cardinal symptoms of hyperthyroidism that lacks the classic adrenergic TS include thermoregulatory dysfunction, altered signs, has also been described [150,151]. Because of mental status, and multi-organ system dysfunction, the life-threatening nature of true TS, early diagno- as shown in Table 4. The diagnosis of TS is suggested by elevated TH levels and suppressed TSH in the proper clinical setting. The magnitude of TH elevation does not Box 3. Differential diagnosis of correlate well with illness severity [152,153]. In the thyrotoxicosis ICU, TH levels may be elevated following the admin- istration of amiodarone or iodinated radiocontrast Common causes agents; TSH may or may not be affected by these interventions. In addition, low TSH levels may reflect Graves’ disease severe NTIS or may follow the administration of Solitary toxic adenoma dopamine or corticosteroids. Signs of chronic hyper- Toxic multinodular goiter thyroid states, such as goiter or ophthalmopathy, may Thyroiditis: (early) Hashimoto’s, silent, also suggest the diagnosis of TS. Although rarely subacute, postpartum required, increased iodine uptake during nuclear thy- Thyrotoxicosis factitia: exogenous roid testing also can be used to support the diagnosis. TH intake The management of TS is complex, and is summa- rized in Box 4. Initial management can be broken Rare causes down into four goal-directed components: (1) support- ive therapy, (2) blocking TH synthesis and release (and TSH-secreting pituitary adenoma peripheral TH conversion), (3) blocking the peripheral Thyroid carcinoma effects of TH, and (4) identifying and treating Struma ovarii - teratoma the precipitating event. Supportive therapy for TS Hydatidiform mole (secretes human involves respiratory support, hemodynamic support, chorionic gonadotropin) sedation, and management of hyperthermia. Pheno- barbital may be preferred for sedation in this setting 598 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

Esmolol: 250 to 500 Mg/kg, Box 4. Management of thyroid storm IV load, then 50 to 100 Mg/kg/min IV Initiate supportive therapy Reserpine: 2.5 to 5 mg, IM, every Tachypnea: oxygen therapy, 4 hours mechanical ventilation Guanethidine: 30 to 40 mg, po, Hypertension: C-blockade (see every 6 hours below), nitroprusside TH Removal: plasmapheresis, Hyperkinesis: benzodiazepines, plasma exchange, charcoal plas- barbiturates ma perfusion, peritoneal dialysis Hyperthermia: IV fluids, cooling Identify and treat underlying cause blanket, antipyretics Definitive therapy (should preferably Block thyroid hormone synthesis occur after patient is rendered and release euthyroid using standard medical Thioureas: block new hormone therapy) synthesis Radioactive iodine Propylthiouracil (PTU): load 600 Surgical thyroidectomy to 1000 mg, then 1200 mg/d, given as 200–300 mg PO q4-6h Methimazole (tapazole): load 60 to 100 mg, then 60 to because it stimulates metabolic clearance of TH by 120 mg/d, 20 to 30 mg, po, inducing hepatic microsomal enzymes. TS-related every 6 to 8 hours hyperthermia may be treated with cool IV fluids, Inorganic iodine: blocks the release antipyretics, or the use of cooling blankets. of preformed hormone. (Note: An early step in the treatment of TS is to establish the use of inorganic iodine will complete blockade of new TH synthesis with thio- necessitate a delay if radioactive ureas. Initial blockade of iodine organification begins iodine therapy is used later.) within 1 hour of treatment. Propylthiouracil (PTU) Saturated solution of potassium remains the drug of choice for TS because it offers the iodide: five drops (250 mg), advantage of inhibiting peripheral conversion of T4 to po, every 6 to 12 hours T3 (methimazole does not). For TS, PTU is adminis- Lugol’s solution: four to eight tered as a 600 to 1000 mg loading dose, followed by drops, po, every 6 hours 1200 mg/d in four to six divided oral doses. Methima- Ipodate (contrast dye): 0.5 to zole, the more potent thiourea, is an acceptable alter- 1.0 g, po, every 12 hours native; it is given as a loading dose of 60 to 100 mg, Iohexol (contrast dye): 0.6 g, IV, followed by a daily dose of 60 to 120 mg in three or every 12 hours four divided doses. If the oral route is unavailable, both Lithium carbonate: 1200 mg/d, thioureas may be administered rectally [154,155]. po, every 6 to 8 hours Although a history of thiourea-related agranulocytosis Block peripheral conversion of T4 to T3 contraindicates therapy, thioureas should be continued PTU in cases of mild adverse drug reactions (eg, rash, Corticosteroids: Hydrocortisone urticaria, mild transaminase elevations) until the 100 mg, IV, every 6 to 8 hours critical stage of TS has resolved. As thyrotoxicosis (or equivalent) improves, thiourea dosages can be gradually lowered Propanolol to more standard ranges: PTU, 100 to 600 mg/day or Ipodate, Iohexol methimazole 5 to 20 mg/day. Block peripheral effects of thyroid Although thioureas are effective in blocking new hormone TH synthesis, they do not block the release of pre- C-adrenergic blockers formed thyroid hormone. This task can be accom- Propanolol: 0.5 to 1.0 mg, IV, plished by using inorganic iodine, which directly every 2 to 3 hours, or 40 to inhibits the release of TH from the gland. Iodine 80 mg, po, every 4 to 8 hours therapy should ideally be administered 2 hours after thioureas, to allow for organification blockade. Com- P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 599 mon dosage formulations for inorganic iodine include definitive treatment. Overall, with advances in diag- saturated solution of potassium iodide (five drops, po, nosis and treatment, mortality from TS that was nearly two to four times per day) and Lugol’s solution (four to 100% in early series [170] may now be less than 20% eight drops, po, three times per day). Iodinated contrast to 30% (see references [148,171,172]). dyes, including ipodate and iohexol, are also effective [156,157]. In addition to blocking TH release, these radiocontrast agents also impair peripheral T4 deiodi- Critical issues in pituitary disease nization to T3 and may antagonize TH binding to nuclear receptors [149]. Lithium therapy (300 mg, po, Pituitary apoplexy every 6 hours) may also be used to block preformed TH release, either alone or in combination with iodine; The term ‘‘pituitary apoplexy’’ describes the life- toxicity may limit its widespread clinical application. threatening clinical syndrome that results from the ‘‘Stress-dose’’ corticosteroids (IV hydrocortisone, sudden infarction of, or hemorrhage into, the pituitary 100 mg, three or four times per day or equivalent) are gland [173]. Typically, apoplexy occurs in the setting also effective in blocking peripheral deiodinization. In of a pre-existing pituitary adenoma, but it can strike cases of Graves’ disease, steroids may also decrease normal glands as well [174]. Most cases of apoplexy TH release by way of immunomodulatory effects. present without a known history of tumor [175] Blocking the peripheral action of TH is another (ie, apoplexy is often the initial presentation of a important component of therapy for TS. b-blockers pituitary adenoma). Clinical factors that may precipi- (eg, propanolol 40–80 mg, po, every 4 to 8 hours) are tate apoplexy include head trauma, radiation therapy, effective for reducing the tachycardia, hypertension, anticoagulation, bromocriptine therapy, and dynamic and adrenergic symptoms that are associated with pituitary function testing. Diabetes mellitus, hemo- thyrotoxicosis. If oral propanolol is ineffective in dialysis, and the peri-partum state may also predispose controlling symptoms, therapeutic options include IV to pituitary hemorrhage [176]. propanolol and esmolol [158,159]. Reserpine and The clinical presentation of pituitary apoplexy is guanethidine, although effective [148,160,161], are extremely variable and ranges from mild, simple head- rarely used because of adverse effects, including ache to sudden coma and circulatory collapse. The hypotension and CNS depression. In life-threatening clinical severity is determined largely by the extent of cases, when medical therapy has proven ineffective, pituitary hemorrhage, necrosis, and local edema. Al- plasmapheresis [162], plasma exchange [163], char- though pituitary hemorrhage can present with acute, coal plasma perfusion [164], and peritoneal dialysis subacute, or chronic symptoms, the term ‘‘apoplexy’’ [165] have all been successfully used to remove is best reserved for life-threatening, clinical presen- circulating TH. tations. Apoplexy most commonly presents with a Following the initiation of supportive therapy and sudden, severe headache, often in a frontal or retro- TH blockade, clinical and biochemical improvement orbital distribution [177,178]. Extravasation of blood should occur within 24 hours, although full recovery and necrotic sellar contents into the subarachnoid from TS may take several days to weeks [166,167]. space may lead to leptomeningeal irritation [176], Mental status is a reasonable indicator of response to which produces a meningitis-like clinical syndrome therapy, as are improvements in thermoregulation, of fever, meningismus, nausea, vomiting, and altered tachycardia, and hemodynamic derangements. Failure mentation. If present, mental status changes are often to improve these parameters within the first few days followed by rapid clinical deterioration [179]. of therapy portends a poor prognosis [167]. Apoplectic signs and symptoms are determined After the critical phase of TS has passed, definitive mostly by the direction and degree of sellar extension antithyroid therapy should be considered. Because of (Table 5). Upward expansion may compress the optic the recent administration of inorganic iodine and chiasm and optic nerves and lead to visual field deficits concerns over excess TH release during therapy, or complete visual loss [178]. Olfactory nerve damage radioactive iodine plays no role in the acute manage- has also been reported [180], whereas compression of ment of TS. In rare cases, definitive therapy with the hypothalamus may lead to abnormal thermoregu- thyroidectomy may be considered during acute, life- lation (fever), disturbed respiration, hypertension, or threatening TS; however, peri-operative clinical man- malignant cardiac arrhythmias [180]. Lateral sellar agement can be exceeding difficult and cardiovascular expansion into the cavernous sinus can damage the or neurologic complications may occur [168,169].In internal carotid artery (ICA) or local cranial nerves most cases, medical therapy should be used to ‘‘cool (CNs) III, VI, V1,V2, and VI, which leads to oph- off’’ patients who have TS for weeks to months before thalmoplegia, diplopia, ptosis, pupillary defects, or 600 P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606

Table 5 have clinical significance during a subacute course; Clinical features of pituitary apoplexy as considered by however, the long half-life of circulating thyroxine anatomic tissue disruption typically precludes an immediate clinical impact. Mechanism Clinical %of Diabetes insipidus (DI), which results from damage (affected structures) presentation cases to the posterior pituitary gland, occurs in only 4% of Local effects cases [183]. When present, DI presents with polyuria, Sella turcica, Headache 76% polydipsia, and hyperosmolar hypernatremia. dura, meninges Nausea, vomiting 21% The key step in diagnosing pituitary apoplexy is to Altered mentation 19% consider its presence. More common CNS disorders, Meningismus 17% including CNS tumors, cerebrovascular accidents Superior (CVA), subarachnoid hemorrhage (SAH), ICA aneu- Optic chiasm, Visual field 62% rysms, and bacterial meningitis, can mimic its clinical optic nerves deficits, blindness presentation. When apoplexy is suspected, the initial Olfactory nerve Disturbed smell, rare anosmia serologic work-up should include a complete blood Hypothalamus Disturbed autonomic 2% count (with differential), coagulation studies, and regulation electrolytes, as well as a baseline cortisol level and Lateral (cavernous sinus) TFTs. Lumbar puncture, although frequently per- Internal carotid artery Altered mentation, 4% formed to ‘‘rule out’’ bacterial meningitis and SAH, seizures, hemiparesis are unreliable in distinguishing these diseases, because a Oculomotor nerve Ophthalmoplegia, 40% pleocytosis, high red blood cell counts, xanthochro- (CN III) diplopia, ptosis, mia, and high CSF protein can be seen in any of these mydriasis conditions [184]. In the end, radiologic studies are Trochlear nerve Ophthalmoplegia, 40%a required to confirm the diagnosis of pituitary apoplexy. (CN IV) diplopia Abducens nerve Ophthalmoplegia, 40%a During an acute event, CT is the preferred modality (CN VI) diplopia [185] because it can rapidly confirm the presence Ophthalmic/maxillary Facial pain, 40%a of acute pituitary bleeding. In the subacute setting, branches, Trigeminal corneal anesthesia MRI offers superior sensitivity and anatomic detail

nerve (CN V1,V2) [186,187]. Inferior (sphenoid sinus) The clinical management of pituitary apoplexy Sphenoid sinus Epistaxis, CSF rare involves supportive management, ‘‘stress-dose’’ cor- rhinorrhea ticosteroid therapy, and rapid neurosurgical consulta- a CN (cranial nerve) palsies are present in approxi- tion. Following cardiopulmonary and hemodynamic mately 40% of cases. There is no available breakdown of stabilization, electrolyte and hydration status should frequency by individual cranial nerve involvement. be monitored carefully for the development of DI. Modified from Rolih CA, Ober KP. Pituitary apoplexy. Hyponatremia also is commonly seen, usually in Endocrinol Metab Clin N Am 1993;22:291–302; with the setting of inappropriate antidiuretic hormone se- permission. cretion, secondary hypoadrenalism, or secondary hy- pothyroidism. Because of the high incidence of facial pain. CN palsies occur in more than 40% of adrenal insufficiency, empiric ‘‘stress-dose’’ cortico- cases. In rare cases of associated ICA spasm, apoplexy steroid therapy (hydrocortisone 100 mg, IV, every 6 to can produce seizures, hemiplegia, and other acute 8 hours; dexamethasone, 4 mg, IV, every 8 hours or signs of cerebrovascular occlusion [181,182]. With equivalent) should be rapidly administered in all cases. inferior expansion into the sphenoid sinus, epistaxis Steroids may also help to reduce intracranial swelling. or cerebral spinal fluid (CSF) rhinorrhea have Finally, emergent neurosurgical consultation is recom- been reported. mended in most cases. Pituitary hormone deficiency is a common conse- Transsphenoidal decompression has been the pre- quence of apoplexy. Hypogonadism, growth hormone ferred neurosurgical approach for pituitary apoplexy (GH) deficiency, and prolactin disturbances all occur [178]. Absolute surgical indications include obtunda- in more than two thirds of cases, but each of these tion, coma, or a rapidly deteriorating clinical course entities has little clinical consequence in the acute [179]; visual loss is also frequently cited as a surgical setting [183]. Acute adrenal insufficiency, which is indication [188]. Most patients who have stable mental also found in two thirds of cases, can be life-threat- status and minimal (or absent) visual impairment will ening and should usually be treated empirically. recover without surgery [189]. In addition, isolated Hypothyroidism is found in 42% of cases and may ophthalmoplegias often resolve with expectant man- P.A. Goldberg, S.E. Inzucchi / Clin Chest Med 24 (2003) 583–606 601 agement [175,189]. Given the growing recognition of [15] Ennis ED, Stahl EJVB, Kreisberg RA. The hyperos- subacute and chronic presentations of pituitary injury, molar hyperglycemic syndrome. 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