Contemporary evaluation and management of Cushing's syndrome

Cushing's syndrome, characterized by unregulated cortisol secretion, may be caused by a variety of adrenal, pituitary, or other tumors. The best biochemical test for establishing the diagnosis is determination of 24-h urinary free cortisol. The specific causes for Cushing's syndrome may be further differentiated by plasma adrenocorticotrophic hormone (ACTH). Primary adrenal cortical diseases are associated with low levels of ACTH and are considered ACTH-independent. Pituitary disease and the ectopic ACTH syndrome are associated with normal or elevated ACTH levels and are considered ACTH-dependent. Adrenal forms of Cushing's syndrome may result from either adenoma or carcinoma. The diagnostic approach to Cushing's syndrome and the clinical, biochemical, and radiographic features that distinguish adrenal adenoma and carcinoma are the subjects of this paper. 65-75% of CS [14, 15]. Most cases of Cushing's disease are the result of pituitary adenomas; however, corticotrope hyperplasia is responsible for a small minority of cases. Ectopic production of ACTH from a variety of tumors (bronchial carciniod, thymoma, oat-cell carcinoma, pheochromocytoma, islet-cell tumor, and prostate cancer) accounts for 10-15% of CS. Primary adrenocortical diseases account for the remaining 20-30% of CS, including benign adenoma (10-15%), adrenocortical carcinoma (5-10%), and adenomatous hyperplasia (5%). The purpose of this review is to present a contemporary approach to the evaluation and management of patients with Cushing's syndrome, emphasizing the primary adrenal etiologies pertinent to urologists.