Contemporary evaluation and management of Cushing's syndrome

Gushing's syndrome, characterized by unregulated cortisol secretion, may be caused by a variety of adrenal, pituitary, or other tumors. The best bioch emical test for establishing the diagnosis is determination of 24-h urinary free cortisol. The specific causes for Cushing's syndrome may be further d ifferentiated by plasma adrenocorticotrophic hormone (ACTH). Primary adrena l cortical diseases are associated with low levels of ACTH and are consider ed ACTH-independent. Pituitary disease and the ectopic ACTH syndrome are as sociated with normal or elevated ACTH levels and are considered ACTH-depend ent. Adrenal forms of Cushing's syndrome may result from either adenoma or carcinoma. The diagnostic approach to Gushing's syndrome and the clinical, biochemical, and radiographic features that distiguish adrenal adenoma and carcinoma are the subjects of this paper.