Addison Disease (cont.)

Less common causes of primary adrenal insufficiency are:

• chronic infection, mainly fungal infections
• cancer cells spreading from other parts of the body to the adrenal glands
• amyloidosis
• surgical removal of the adrenal glands

This form of adrenal insufficiency is much more common than primary adrenal insufficiency and can be traced to a lack of ACTH. Without ACTH to stimulate the adrenals, the adrenal glands' production of cortisol drops, but not aldosterone. A temporary form of secondary adrenal insufficiency may occur when a person who has been receiving a glucocorticoid hormone such as prednisone for a long time abruptly stops or interrupts taking the medication. Glucocorticoid hormones, which are often used to treat inflammatory illnesses like rheumatoid arthritis, asthma, or ulcerative colitis, block the release of both corticotropin-releasing hormone (CRH) and ACTH. Normally, CRH instructs the pituitary gland to release ACTH. If CRH levels drop, the pituitary is not stimulated to release ACTH, and the adrenals then fail to secrete sufficient levels of cortisol.

Another cause of secondary adrenal insufficiency is the surgical removal of benign, or noncancerous, ACTH-producing tumors of the pituitary gland (Cushing's disease). In this case, the source of ACTH is suddenly removed, and replacement hormone must be taken until normal ACTH and cortisol production resumes.

Less commonly, adrenal insufficiency occurs when the pituitary gland either decreases in size or stops producing ACTH. These events can result from:

• tumors or infections of the area
• loss of blood flow to the pituitary
• radiation for the treatment of pituitary tumors
• surgical removal of parts of the hypothalamus
• surgical removal of the pituitary gland

Source: MedicineNet.com
http://www.medicinenet.com/addison_disease/article.htm