A hormone which produced by the adrenal gland (cortex) to control blood sugar. The production of cortisol is triggered by the pituitary hormone ACTH. Cortisol is a glucocorticoid which stimulates an increase in blood glucose. Cortisol will also stimulate the release of amino acids from muscle tissue and fatty acids from adipose tissue. The amino acids are then converted in the liver to glucose (for use by the brain). The fatty acids can be used by skeletal muscles for energy (rather that glucose) thereby freeing up glucose for selective utilization by the brain. Cortisol levels are often measured to evaluate the function of the pituitary or adrenal glands. Some of the cortisol is metabolized by the liver to produce 17 hydroxycorticosteroids, which is then excreted in the urine. Often elevated in blood group A individuals when under stress.