Addison's disease, also known as primary adrenal insufficiency and hypocortisolism, is a rare long-term endocrine disorder characterized by inadequate production of the steroid hormones cortisol and aldosterone by the two outer layers of the cells of the adrenal glands (adrenal cortex), causing renal insufficiency. Symptoms generally come on slowly and may include abdominal pain and gastrointestinal abnormalities, weakness, and weight loss. [Source: Wikipedia ]