is the major glucocorticoid produced and secreted by the adrenal cortex. It affects the metabolism of protein, fat and carbohydrates; the maintenance of muscle and myocardial integrity; and the suppression of inflammatory and allergic activities. Production of cortisol from the adrenal cortex is dependent upon corticotrophin (ACTH), which is secreted by the anterior pituitary. The corticotrophin releasing factor (CRF) which regulates ACTH is secreted by the hypothalamus and is responsive to cortisol levels. Physical, psychological and surgical stress and diurnal variation will affect the rate of cortisol production. Corticosteroid-binding globulin and albumin bind approximately 90% of the cortisol secreted by the adrenal cortex. Bound cortisol circulates in an available but temporarily inactive state. The physiological activity of cortisol depends upon levels of the small fraction of circulating unbound cortisol.