Cortisol is a hormone, a chemical that regulates body function. It is produced by the adrenal glands, which are located above each kidney. Cortisol helps regulate blood sugar levels and the responses to infection and stress. Cortisol production is increased by adrenocorticotropic hormone(ACTH) released from the pituitary gland in the brain. Hypercortisolemia (cortisol overproduction) causes Cushing syndrome, most often when a pituitary adenoma (a benign tumor) produces an excess of ACTH, resulting in Cushing disease. It also results when an adenoma of the adrenal gland produces too much cortisol. Both Cushing syndrome and Cushing disease affect women more often than men. Rarely, hypercortisolemia is produced by a tumor outside the pituitary or adrenal glands; for example, by a lung cancer that releases ACTH. This is called ectopic Cushing syndrome. Cushing syndrome can develop as part of genetic diseases that run in families (such as multiple endocrine neoplasia type 1). Prolonged treatment with glucocorticoids, which are cortisol-like drugs, can result in iatrogenic Cushing syndrome.