Chronic underfunction of the outer portion of the adrenal gland, most commonly due to autoimmune destruction. Other causes include physical trauma to the adrenal gland, hem- orrhage, tuberculosis, and destruction of the pitu- itary gland cells that secrete adrenocorticotropic hormone (ACTH), which normally controls the adrenal gland. Addison’s disease is characterized by bronzing of the skin, anemia, weakness, and low blood pressure.