Excerpt from Adrenal Insufficiency and Adrenal Crisis

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Background

Adrenal crisis and severe acute adrenocortical insufficiency are often elusive diagnoses that may result in severe morbidity and mortality when undiagnosed or ineffectively treated.

Although more than 50 steroids are produced within the adrenal cortex, cortisol and aldosterone are by far the most abundant and physiologically active. In primary adrenocortical insufficiency, glucocorticoid and mineralocorticoid properties are lost; however, in secondary adrenocortical insufficiency (ie, secondary to disease or suppression of the hypothalamic-pituitary axis), mineralocorticoid function is preserved.

Although suppression of the hypothalamic-pituitary axis from chronic exogenous steroid use is the most common cause of secondary adrenal insufficiency, the possibility of hypopituitarism due to hypothalamic-pituitary disease must be considered. With acute hypopituitarism, other hormone deficiencies must be identified and treated in addition to treating adrenal insufficiency with corticosteroids. For instance, if a patient with pan-hypopituitarism from Sheehan syndrome (postpartum pituitary infarction) is only treated for adrenal crisis, severe cardiovascular compromise from the untreated associated hypothyroidism will probably occur. Death can result if the hypothyroid state is not diagnosed.

Every emergency physician should be familiar with adrenocortical insufficiency—a potentially life-threatening entity. The initial diagnosis and decision to treat are presumptive and are based on history, physical examination, and, occasionally, laboratory findings. Delay in treatment while attempting to confirm this diagnosis can result in poor patient outcomes.

For a CME/CE activity, see Endocrine Emergencies.

Pathophysiology

Adrenal medullae normally secrete 80% epinephrine and 20% norepinephrine. Sympathetic stimulation results in secretion.

The adrenal cortex produces cortisol, aldosterone, and androgens. Cortisol is produced from 2 hydroxylations of 17alpha-hydroxyprogesterone. Cortisol, also known as hydrocortisone, is 90-93% protein bound (primarily by corticosteroid-binding globulin).

Physiologic effects of glucocorticoids

Glucocorticoids are nonspecific cardiac stimulants that activate release of vasoactive substances. In the absence of corticosteroids, stress results in hypotension, shock, and death. Glucocorticoids act as follows to:

• Stimulate gluconeogenesis and decrease cellular glucose use
• Mobilize amino acids and fatty acids
• Inhibit the effects of insulin
• Give rise to ketone bodies in metabolism (ketogenesis)
• Elevate RBC and platelet levels
• Exhibit anti-inflammatory effects, including the following:
• • Maintenance of normal vascular response to vasoconstrictors
  • Opposition to increases in capillary permeability
  • Inhibition of interleukin-2 (IL-2) production by macrophages
  • Stimulation of polymorphonuclear neutrophil (PMN) leukocytosis
  • Reduction of adherence of macrophages to endothelium
  • Depletion of circulating eosinophils and lymphocytes
  • Reduction of circulating lymphocytes (primarily T cells)

Physiologic effects of aldosterone

Aldosterone is produced by multiple hydroxylations of deoxycorticosterone and is normally 60% protein bound. The renin-angiotensin system stimulates aldosterone release. Increased potassium stimulates aldosterone production, and decreased potassium inhibits production. Chronic adrenocorticotropic hormone (ACTH) deficiency may inhibit production.

The primary actions of aldosterone cause the kidneys, gut, and salivary/sweat glands to affect electrolyte balance. The primary targets are the kidneys; these organs stimulate reabsorption of sodium and secretion of potassium and hydrogen ions. The kidneys' effect on sodium and potassium depend on the intake of these cations (ie, increased sodium intake = increased potassium secretion). The effects on hydrogen probably can occur independently.

Persistent aldosterone excess results in atrial natriuretic factor release and renal hemodynamic changes for compensation. Congestive heart failure (CHF) and cirrhosis with ascites are exceptions that cause progressive sodium retention. Excess aldosterone results in sodium retention, hypokalemia, and alkalosis. Aldosterone deficiency results in sodium loss, hyperkalemia, and acidosis. Hyperkalemia stimulates aldosterone release to improve potassium excretion. Aldosterone is the first-line defense against hyperkalemia.

Primary adrenal insufficiency

Primary adrenal insufficiency, which can be acute or chronic, may be caused by the anatomic destruction of the gland. This destruction can have various causes, including tuberculosis (TB) or fungal infection, other diseases infiltrating the adrenal glands, and hemorrhage. However, the most frequent cause is idiopathic atrophy, which is probably autoimmune in origin.

Primary adrenal insufficiency also may be caused by metabolic failure (eg, insufficient hormone production). This failure may be a result of congenital adrenal hyperplasia, enzyme inhibitors (eg, metyrapone), or cytotoxic agents (eg, mitotane).

Primary adrenocortical insufficiency is rare and it occurs at any age. The male-to-female ratio is 1:1.

Secondary adrenal insufficiency

Secondary adrenal insufficiency may be caused by hypopituitarism due to hypothalamic-pituitary disease, or it may result from suppression of the hypothalamic-pituitary axis by exogenous steroids or endogenous steroids (ie, tumor).

Secondary adrenocortical insufficiency is relatively common. Extensive therapeutic use of steroids has greatly contributed to increased incidence.

Acute adrenocortical insufficiency

Adrenal crisis may result from an acute exacerbation of chronic insufficiency, usually caused by sepsis or surgical stress. Acute adrenal insufficiency also can be caused by adrenal hemorrhage (eg, usually septicemia-induced Waterhouse-Friderichsen syndrome [fulminant meningococcemia]) and anticoagulation complications. Steroid withdrawal is the most common cause of acute adrenocortical insufficiency, and it almost exclusively causes a glucocorticoid deficiency.

Frequency

United States

Primary adrenocortical insufficiency is an uncommon disorder with an incidence in Western populations near 50 cases per 1,000,000 persons. With the advent of widespread corticosteroid use, however, secondary adrenocortical insufficiency due to steroid withdrawal is much more common. Approximately 6,000,000 persons in the United States are considered to have undiagnosed adrenal insufficiency, which is clinically significant only during times of physiologic stress.

• Primary adrenocortical insufficiency has multiple etiologies; however, 80% of cases in the United States are caused by autoimmune adrenal destruction. Glandular infiltration by tuberculosis is the second most frequent etiology.
• In patients with primary adrenocortical insufficiency due to idiopathic autoimmune lymphocytic infiltration, the presence of other associated endocrine disorders must be entertained. Consider polyglandular autoimmune disorders (PGAs) such as Schmidt syndrome.
• Schmidt syndrome (PGA type II) includes adrenal insufficiency, autoimmune thyroid disease, and, occasionally, insulin-dependent diabetes mellitus. Adrenal insufficiency usually occurs in these patients when they are older than 20 years. In approximately 40-50% of patients with PGA II, the first manifestation of the syndrome is adrenal insufficiency.
• PGA type I includes hypoparathyroidism and mucocutaneous candidiasis in conjunction with adrenal insufficiency. The full triad may manifest in approximately 30% of patients with PGA type I.

Mortality/Morbidity

• Acute adrenocortical insufficiency is a difficult diagnosis to make. The disorder rarely occurs without concomitant injury or illness. Many of the presenting signs and symptoms are nonspecific. For instance, a postoperative fever may presumptively be treated as infection or systemic inflammatory response syndrome when it may be a subtle indicator of adrenal insufficiency.
• Left untreated, a patient with acute adrenal insufficiency has a dismal prognosis for survival. Therefore, treatment upon clinical suspicion is mandatory. Any delay in management while waiting for diagnostic confirmation cannot be justified.

Sex

Although primary adrenocortical insufficiency affects men and women equally, women are affected 2-3 times more often by the idiopathic autoimmune form of adrenal insufficiency.

Age

In idiopathic autoimmune adrenal insufficiency, the diagnosis is most often discovered in the third to fifth decades of life; however, it is particularly important to recognize that adrenocortical insufficiency is not limited to any specific age group.

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