Cushing's syndrome

Cushing's syndrome is the disorder that results from too much cortisol acting on the body over a long time, no matter where the excess comes from. Because cortisol touches almost every tissue, chronic excess produces a distinctive and wide-ranging picture: weight gain centered on the trunk and face, a rounded face, fragile skin that bruises easily, purple stretch marks, muscle weakness, high blood sugar, high blood pressure, and mood changes.

The most common cause overall is medical: taking glucocorticoid drugs for another condition. When the cause is the body's own overproduction, it is divided by source. ACTH-dependent forms include a pituitary tumor secreting too much ACTH (called Cushing's disease, the most common endogenous cause) and ectopic ACTH from a tumor elsewhere. ACTH-independent forms arise from the adrenal gland itself overproducing cortisol, as from an adrenal tumor.

Diagnosis first confirms genuine cortisol excess — using tests such as late-night salivary cortisol, 24-hour urine cortisol, or the dexamethasone suppression test — then works out the source by measuring ACTH and imaging. Treatment targets the cause: surgery for a tumor, or tapering the offending medication. Left untreated, the chronic excess carries serious cardiovascular, metabolic, and infectious risks.