Diagnosis and pathophysiology of Cushing's syndrome

Cushing's syndrome is the consequence of a sustained overproduction of cortisol (hydrocortisone) by the adrenal cortex. This may be due to excessive secretion of cortisol by functioning adrenocortical tumors or to "nontumorous" adrenocortical hyperfunction. The latter may be a result of stimulation of the adrenal cortex by increased release of corticotropin (ACTH) from a small pituitary tumor or from nonpituitary nonadrenal tumor. Carcinoids or carcinomas of the lung or pancreas, and even pheochromocytomas have caused the syndrome of ectopic ACTH production. The problems involved in the diagnosis of Cushing's syndrome are establishing its presence and determining the underlying cause. Treatment is then dependent upon the underlying pathogenetic lesion.