Addison's Disease

The adrenal glands, also called suprarenal glands, sit like flat, triangular caps atop each kidney. They are divided into two distinct areas-the medulla at the center and cortex surrounding the outside. The cortex, which makes up about 80% of the adrenal gland, secretes three types of hormones—sex hormones, mineralocorticoids (principally aldosterone), and glucocorticoids (primarily cortisol or hydrocortisone). Scientists believe these hormones perform hundreds of regulatory functions in the body, including helping to regulate metabolism, blood pressure, the effects of insulin in the breakdown of sugars, and the inflammatory response of the immune system. Addison's disease results from an injury or disease that slowly destroys the adrenal cortex, therefore shutting down the production of these hormones.

The production of cortisol by the adrenal cortex is precisely metered by a control loop that begins in an area in the brain called the hypothalamus, a collection of specialized cells that control many of the functions of the body. When necessary, the hypothalamus secretes a releasing factor that tells the pituitary gland to secrete another hormone to stimulate the adrenal gland to release more cortisol. The increased cortisol levels signal the pituitary to stop producing the adrenal stimulant. This is a finely tuned loop, and if it is interrupted or shut down, as in Addison's disease, profound changes occur in the body.