Predisposing factors for adrenal insufficiency.

N Engl J Med 2009;360:2328-39. Copyright © 2009 Massachusetts Medical Society. A drenal insufficiency — the clinical manifestation of deficient production or action of glucocorticoids — is a life-threatening disorder that may result from either primary adrenal failure or secondary adrenal disease due to impairment of the hypothalamic–pituitary axis.1,2 This article focuses on providing the practicing clinician with new insights into predisposing factors for adrenal insufficiency. When and during what situations should a clinician suspect adrenal insufficiency? What genetic disorders, infections, and medications should be considered? What are the current views on the underlying mechanisms? The cardinal clinical symptoms of adrenocortical insufficiency, as first described by Thomas Addison in 1855,3 include weakness, fatigue, anorexia, and abdominal pain, with orthostatic hypotension, salt craving, and characteristic hyperpigmentation of the skin occurring with primary adrenal failure. The acute syndrome constitutes a medical emergency since it may result in a severe hypotensive crisis and clouded sensorium, together with pain in the muscles, joints, or abdomen and fever.1,2 In the diagnostic workup for the disorder, the capacity of the adrenal cortex to respond to corticotropin is tested with the use of the standard short corticotropin test, which measures the serum cortisol level before and 30 or 60 minutes after an intravenous or intramuscular injection of 250 μg of corticotropin.4 An increase in the serum cortisol level to peak concentrations above 500 nmol per liter (18 μg per deciliter) indicates a normal response. The adrenal responsiveness to an exogenous corticotropin challenge is impaired in most cases of secondary adrenal disease. With mild secondary adrenal insufficiency, however, the hypothalamic–pituitary– adrenal axis may appear intact, with a normal response to a corticotropin challenge. Recent evidence suggests that the 1-μg corticotropin stimulation test is more sensitive than the 250-μg corticotropin test for establishing the diagnosis of secondary adrenal insufficiency.5 Once adrenal insufficiency is diagnosed, glucocorticoid replacement is initiated in two or three daily doses; one half to two thirds of the daily dose (15 to 25 mg of hydrocortisone) is given in the morning, in line with the physiologic cortisol-secretion pattern. Mineralocorticoid replacement (0.05 to 0.2 mg of fludrocortisone daily as a morning dose) is required only in the case of primary adrenal insufficiency, and dehydroepiandrosterone replacement (25 to 50 mg) remains an optional treatment.1,2 Management of an acute adrenal crisis consists of immediate intravenous administration of 100 mg of hydrocortisone, followed by 100 to 200 mg of hydrocortisone every 24 hours and a continuous infusion of larger volumes of physiologic saline solution (initially 1 liter per hour) under continuous cardiac monitoring. Timely diagnosis and clinical management of this condition are critical, and physicians in all areas of medicine should be aware of the causes, signs, and symptoms that herald adrenal insufficiency.