Causes of Adrenal Insufficiency
Approximately 50 percent of people with primary adrenal insufficiency have more than one autoimmune endocrine disorder. This is called polyendocrine deficiency syndrome. The polyendocrine deficiency syndrome is classified into two separate forms, referred to as type I and type II.
Type I occurs in children, and adrenal insufficiency may be accompanied by:
- Underactive parathyroid glands (hypoparathyoidism)
- Slow sexual development
- Pernicious anemia
- Chronic candida infections
- Chronic active hepatitis
- Hair loss (in very rare cases).
Type II, often called Schmidt's syndrome, usually afflicts young adults. Features of type II may include:
- An underactive thyroid gland (hypothyroidism)
- Slow sexual development
- Type 1 diabetes
- Loss of pigment on areas of the skin.
Scientists think that the polyendocrine deficiency syndrome is inherited because frequently, more than one family member tends to have one or more endocrine deficiencies.
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 they continue to produce 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 non-cancerous, 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, secondary 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.