Cushing's Syndrome

Definition

Cushing's Syndrome is a disorder caused by prolonged exposure to excessive cortisol, either endogenous (from the body) or exogenous (from glucocorticoid therapy). It results in characteristic metabolic, musculoskeletal, cardiovascular, and dermatologic manifestations.

Epidemiology

• Incidence: ~2–3 per million per year
• More common in adults aged 20–50 years
• Female predominance (3:1 female to male ratio)
• Exogenous glucocorticoid use is the most common cause overall

Etiology

• Exogenous corticosteroid therapy (most common overall)
• Endogenous causes:
• - ACTH-dependent: Pituitary adenoma (Cushing's disease), Ectopic ACTH secretion
• - ACTH-independent: Adrenal adenoma, adrenal carcinoma, nodular adrenal hyperplasia

Pathophysiology

• Excess cortisol → protein catabolism, gluconeogenesis, insulin resistance
• Mineralocorticoid effects → sodium retention, hypertension
• Immunosuppressive effects → increased infection risk
• Altered fat distribution → central obesity, 'moon face', 'buffalo hump'