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Addison's disease

Addison’s disease is a disorder of the adrenal glands. The adrenal glands are small, hat-shaped glands that sit on top of the kidneys, high up inside the back of the abdominal wall.

The adrenal glands have two functions. The inner area, called the medulla, produces the hormone adrenaline, and passes it into the bloodstream. Adrenaline increases the action of the heart and speeds up metabolism, preparing the body for shock.

The outer layer, called the cortex, produces steroids. One of the steroids it produces is cortisol, which increases the supply of glucose in the blood. Along with adrenaline, cortisol acts to help the body cope with stress. Over-production of cortisol can be harmful to the immune system. Another steroid produced by the cortex is aldosterone. Aldosterone helps to maintain blood pressure by keeping sodium (salt) levels up in the blood. Finally, the adrenal cortex produces the male sex hormone testosterone.

In people with Addison’s disease, the adrenal cortex is destroyed, leading to a deficiency or absence of the hormones it produces.