What is Addison's disease?
Addison's disease (also known as chronic adrenal insufficiency, or hypocortisolism) is a rare endocrine disorder. It is estimated that it affects about 1 to 5 in 100,000 people. It occurs when the adrenal glands, seated above the kidneys, fail to produce enough of the hormone cortisol and, sometimes, the hormone aldosterone. Addison's disease refers specifically to
primary adrenal insufficiency, in which the adrenal glands themselves malfunction; secondary adrenal insufficiency occurs when the pituitary gland does not produce enough adrenocorticotropic hormone (ACTH) to adequately stimulate the adrenal glands.
Addison's disease is a rare endocrine, or hormonal disorder that affects about 1 in 100,000 people. It occurs in all age groups and afflicts men and women equally. The disease is characterized by weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin in both exposed and nonexposed parts of the body. Addison's disease occurs when the adrenal glands do not produce enough of the hormone cortisol and in some cases, the hormone aldosterone. For this reason, the disease is sometimes called chronic adrenal insufficiency, or hypocortisolism.
Cortisol is normally produced by the adrenal glands, located just above the kidneys. It belongs to a class of hormones called glucocorticoids, which affect almost every organ and tissue in the body. Scientists think that cortisol has possibly hundreds of effects in the body. Cortisol's most important job is to help the body respond to stress. Among its other vital tasks, cortisol helps maintain blood pressure and cardiovascular function, helps slow the immune system's inflammatory response, helps balance the effects of insulin in breaking down sugar for energy, and helps regulate the metabolism of proteins, carbohydrates, and fats.
Because cortisol is so vital to health, the amount of cortisol produced by the adrenals is precisely balanced. Like many other hormones, cortisol is regulated by the brain's hypothalamus and the pituitary gland, a bean-sized organ at the base of the brain. First, the hypothalamus sends "releasing hormones" to the pituitary gland. The pituitary responds by secreting other hormones that regulate growth, thyroid and adrenal function, and sex hormones such as estrogen and testosterone. One of the pituitary's main functions is to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands. When the adrenals receive the pituitary's signal in the form of ACTH, they respond by producing cortisol. Completing the cycle, cortisol then signals the pituitary to lower secretion of ACTH.
Aldosterone belongs to a class of hormones called mineralocorticoids, also produced by the adrenal glands. It helps maintain blood pressure and water and salt balance in the body by helping the kidney retain sodium and excrete potassium. When aldosterone production falls too low, the kidneys are not able to regulate salt and water balance, causing blood volume and blood pressure to drop.
Addison's disease is also called primary adrenocortical insufficiency. In other words, some process interferes directly with the ability of the adrenal cortex to produce its hormones. Levels of both cortisol and aldosterone drop, and numerous functions throughout the body are disrupted.