Cortisol, or hydrocortisone, is the primary corticosteroid secreted by the adrenal cortex. Cortisol is synthesized from cholesterol and may be found in the blood as free Cortisol or bound to corticosteroid-binding globulin. The release of Cortisol is controlled by ACTH, which is produced in the anterior pituitary. Plasma Cortisol levels are highest in the morning and decrease throughout the day. Cortisol concentration in the plasma also elevates in response to stress. Cortisol has an antiinflammatory effect and aids in carbohydrate metabolism, renal function and the promotion of glucogenesis. Measurement of plasma Cortisol levels is useful in diagnosing conditions related to functions of the adrenal cortex, including Cushing's syndrome (hypercortisolism), Addison's disease (hypocortisolism) and adrenal tumors. Abnormal Cortisol levels may also possibly be linked to prostate cancer, depression, and schizophrenia.