Endocrinopathies of hyperfunction: Cushing's syndrome and aldosteronism

Increased function of the adrenal cortex is a normal response in times of physiologic and psychologic stress. Adrenal cortical secretions (e.g., glucocorticoids, aldosterone) orchestrate a multitude of internal processes aimed at maintaining homeostasis and psychologic integrity. Many patients admitted to a critical care unit will manifest some increase, even minor, in adrenal function. However, excessive secretions of these hormones can have a lethal effect of fluid and electrolyte balance, energy metabolism, and immune function. Cushing's syndrome denotes a disorder characterized by increased circulating levels of glucocorticoids (primarily cortisol). An easily recognizable disorder, it may arise from pathology of the adrenal cortex or the anterior pituitary glands, ectopic secretions from a nonendocrine tumor, or from excessive doses of exogenously administered glucocorticoids. Cushing's syndrome is rarely an admitting diagnosis to critical care but is a disorder that can seriously affect recovery from coexisting illnesses if not treated. Aldosteronism, although rare, will often be diagnosed after admission to a critical care unit for management of troublesome hypertension, hypokalemia, congestive heart failure, and various dysrhythmias. Suspicion of the diagnosis should always arise when these manifestations occur, particularly when hypokalemia is refractory to potassium supplementation. Without timely diagnosis and treatment, these patients will succumb to lethal dysrhythmias.