The adrenal glands are small organs that sit atop each of the kidneys. They produce hormones that are important in regulating the levels of sodium in the blood, the development of sexual characteristics and the body's response to stress. When the adrenal gland fails to supply adequate amounts of hormone, symptoms such as fatigue, muscle weakness and weight loss can ensue. A variety of different factors can affect the adrenal gland's ability to produce hormones and result in adrenal insufficiency.
Autoimmune Disorders
Sometimes the immune system misidentifies healthy adrenal tissue as being an antigen, meaning a foreign body that poses a threat to human health. The immune system reacts by mounting a defensive response against the adrenal gland. This phenomenon, wherein the body attacks its own healthy cells, is called an autoimmune disorder.
Addison's disease is a common cause of adrenal insufficiency. The National Endocrine and Metabolic Diseases Information Service states that 80 percent of all cases of Addison's disease are caused by an autoimmune reaction. Adrenal insufficiency occurs after the majority of adrenal cortical cells have been destroyed, leaving l0 percent or less in functioning order.
Infection
Various types of infection can attack the adrenal gland, destroying the cortex and causing a drastic decrease in the production of hormones. Fungal infections, AIDS-associated infections and tuberculosis bacilli are among the pathogens known to influence the adrenal gland's ability to produce hormone.
Tuberculosis was once the leading cause of adrenal insufficiency, but advances in the treatment of the disease have greatly decreased the number of instances where TB has resulted in this disorder.
ACTH Deficiency
The hypothalamus and pituitary glands are located in the brain, but they have the power to influence the function of the adrenal gland. The Merck Manuals Online Medical Library explains that secondary adrenal insufficiency is due to a failure of the pituitary gland to secrete adequate amounts of adrenocorticotropin, or ACTH. ACTH stimulates the adrenal gland to release adrenal hormones. A deficiency in ACTH results in a deficiency in adrenal hormones.
Decrease in CRH
Farther up the endocrine system's chain of command, the hypothalamus exerts an influence over the pituitary gland through the secretion of corticotropin-releasing hormone, or CRH. A decrease in CRH leads to a decrease in ACTH, and in turn, a decrease in adrenal hormones, thus causing tertiary adrenal insufficiency.
