Addison's Disease is an uncommon disease, caused by partial or complete failure of the outer layer of the adrenal glands (the adrenal cortex).
The adrenal gland produces hormones that control many body functions. In Addison's disease, there is a chronic deficiency of cortisol, aldosterone and adrenal androgens (hormones made in the adrenal glands). When the body is deficient in these hormones, the result can be high levels of potassium and low levels of salt, causing an electrolyte imbalance in the body.
The Importance Of Cortisol
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, 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, slow the immune system's inflammatory response, balance the effect of insulin in breaking down sugar for energy and 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. One of the pituitary's main functions is to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands.
Failure to produce adequate amounts of cortisol (or adrenal insufficiency) can occur for different reasons. The problem may be due to a disorder of the adrenal glands themselves (primary adrenal insufficiency) or to an inadequate secretion of ACTH by the pituitary gland (secondary adrenal insufficiency). Autoimmune destruction of the adrenals is the most common form of Addison’s disease in the U.S. (80 percent of all cases). It may occur alone or as part of a syndrome. Other causes include adrenal hemorrhage (bleeding), tuberculosis and genetic disorders.
The symptoms of adrenal insufficiency usually begin gradually. Worsening chronic fatigue and muscle weakness, loss of appetite and weight loss are characteristic of the disease. Nausea, vomiting and diarrhea occur in about 50 percent of all cases. Blood pressure is low and falls further when standing, causing dizziness or fainting.
Skin changes are also common in Addison's disease, with areas of hyperpigmentation (or dark tanning) covering exposed and nonexposed parts of the body. This darkening of the skin is most visible on scars, skin folds and pressure points, such as the elbows, knees, knuckles, toes, lips and mucous membranes.
Addison's disease can cause irritability and depression. Because of salt loss, craving of salty foods is also common. Hypoglycemia (or low blood sugar) is more severe in children than in adults. In women, menstrual periods may become irregular or stop completely.
Because the symptoms progress slowly, they are usually ignored until a stressful event like an illness or an accident causes them to become worse. This is called an Addisonian crisis, or acute adrenal insufficiency. In most patients, symptoms are severe enough to seek medical treatment before a crisis occurs. However, in 25 percent of all patients, symptoms do not appear until an Addisonian crisis. Symptoms of an Addisonian crisis include sudden penetrating pain in the lower back, abdomen or legs, severe vomiting and diarrhea, followed by dehydration, low blood pressure and loss of consciousness.
Diagnosis is based on medical history, symptoms, physical examination and blood tests (often cortisol and ACTH).
Treatment includes a combination of glucocorticoids and mineralocorticoids to replace the adrenal insufficiency. Hydrocortisone and fludrocortisone are commonly prescribed. In addition, all infections must be treated aggressively. The dose of glucocorticoids is raised in case of trauma, surgery, stressful diagnostic procedures or other forms of stress. Patients should wear a medical alert bracelet stating “Adrenal insufficiency—takes hydrocortisone.”
A full and active life is possible for most patients.
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