Article title: Addison's Disease: NIDDK
Main condition: Addison's Disease
Conditions: Addison's Disease, adrenal, addisonian crisis
Date: 12 February 1998
Source: NIDDK
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:
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.
Primary Adrenal Insufficiency
Most cases of Addison's disease are caused by the gradual destruction of the adrenal cortex, the outer layer of the adrenal glands, by the body's own immune system. About 70 percent of reported cases of Addison's disease are due to autoimmune disorders, in which the immune system makes antibodies that attack the body's own tissues or organs and slowly destroy them. Adrenal insufficiency occurs when at least 90 percent of the adrenal cortex has been destroyed. As a result, often both glucocorticoid and mineralocorticoid hormones are lacking. Sometimes only the adrenal gland is affected, as in idiopathic adrenal insufficiency; sometimes other glands also are affected, as in the 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, slow sexual development, pernicious anemia, chronic candida infections, chronic active hepatitis, and, in very rare cases, hair loss. Type II, often called Schmidt's syndrome, usually afflicts young adults. Features of type II may include an underactive thyroid gland, slow sexual development, and diabetes mellitus. About 10 percent of patients with type II have vitiligo, or 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.
Tuberculosis (TB) accounts for about 20 percent of cases of primary adrenal insufficiency in developed countries. When adrenal insufficiency was first identified by Dr. Thomas Addison in 1849, TB was found at autopsy in 70 to 90 percent of cases. As the treatment for TB improved, however, the incidence of adrenal insufficiency due to TB of the adrenal glands has greatly decreased.
Less common causes of primary adrenal insufficiency are chronic infections, mainly fungal infections; cancer cells spreading from other parts of the body to the adrenal glands; amyloidosis; and surgical removal of the adrenal glands. Each of these causes is discussed in more detail below.
Secondary Adrenal Insufficiency
This form of Addison's disease can be traced to a lack of ACTH, which causes a drop in the adrenal glands' production of cortisol 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. This can result from tumors or infections of the area, loss of blood flow to the pituitary, radiation for the treatment of pituitary tumors, or surgical removal of parts of the hypothalamus or the pituitary gland during neurosurgery of these areas.
Addison's disease can cause irritability and depression. Because of salt loss, craving of salty foods also is common. Hypoglycemia, or low blood sugar, is more severe in children than in adults. In women, menstrual periods may become irregular or stop.
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 about 25 percent of patients, symptoms first appear during 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. Left untreated, an addisonian crisis can be fatal.
A diagnosis of Addison's disease is made by biochemical laboratory tests. The aim of these tests is first to determine whether there are insufficient levels of cortisol and then to establish the cause. X-ray exams of the adrenal and pituitary glands also are useful in helping to establish the cause.
When the response to the short ACTH test is abnormal, a "long" ACTH stimulation test is required to determine the cause of adrenal insufficiency. In this test, synthetic ACTH is injected either intravenously or intramuscularly over a 48- to 72-hour period, and blood and/or urine cortisol are measured the day before and during the 2 to 3 days of the injection. Patients with primary adrenal insufficiency do not produce cortisol during the 48- to 72-hour period; however, patients with secondary adrenal insufficiency have adequate responses to the test on the second or third day.
In patients suspected of having an addisonian crisis, the doctor must begin treatment with injections of salt, fluids, and glucocorticoid hormones immediately. Although a reliable diagnosis is not possible while the patient is being treated, measurement of blood ACTH and cortisol during the crisis and before glucocorticoids are given is sufficient to make the diagnosis. Once the crisis is controlled and medication has been stopped, the doctor will delay further testing for up to 1 month to obtain an accurate diagnosis.
If secondary adrenal insufficiency is the cause, doctors may use different imaging tools to reveal the size and shape of the pituitary gland. The most common is the CT scan, which produces a series of x-ray pictures giving a cross-sectional image of a body part. The function of the pituitary and its ability to produce other hormones also are tested.
During an addisonian crisis, low blood pressure, low blood sugar, and high levels of potassium can be life threatening. Standard therapy involves intravenous injections of hydrocortisone, saline (salt water), and dextrose (sugar). This treatment usually brings rapid improvement. When the patient can take fluids and medications by mouth, the amount of hydrocortisone is decreased until a maintenance dose is achieved. If aldosterone is deficient, maintenance therapy also includes oral doses of fludrocortisone acetate.
Surgery
Patients with chronic adrenal insufficiency who need surgery with general anesthesia are treated with injections of hydrocortisone and saline. Injections begin on the evening before surgery and continue until the patient is fully awake and able to take medication by mouth. The dosage is adjusted until the maintenance dosage given before surgery is reached.
Pregnancy
Women with primary adrenal insufficiency who become pregnant are treated with standard replacement therapy. If nausea and vomiting in early pregnancy interfere with oral medication, injections of the hormone may be necessary. During delivery, treatment is similar to that of patients needing surgery; following delivery, the dose is gradually tapered and the usual maintenance doses of hydrocortisone and fludrocortisone acetate by mouth are not reached until about 10 days after childbirth.
It is very helpful for persons with medical problems to wear a descriptive warning bracelet or neck chain to alert emergency personnel. Bracelets and neck chains can be obtained from:
Medic Alert Foundation International
2323 Colorado
Turlock,
California 95381
(209) 668-3333
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Bravo, Emmanuel L., "Adrenocortical Insufficiency," in Conn's Current Therapy, edited by Robert E. Rakel. Philadelphia, W.B. Saunders Company, 1987, pp 493-495.
Bondy, Philip K., "Disorders of the Adrenal Cortex," in Williams Textbook of Endocrinology, seventh edition, edited by Jean D. Wilson and Daniel W. Foster. Philadelphia, R.B. Saunders Company, 1985, pp 844-858.
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Williams, Gordon H. and Dluhy, Robert G., "Diseases of the Adrenal Cortex," in Harnson's Principles of Internal Medicine, 11th edition, edited by Eugene Braunwald, Kurt J. Isselbacher, Robert G. Petersdorf, Jean D. Wilson, Joseph B. Martin, and Anthony S. Fauci. New York, McGraw-Hill Book Company, 1987, pp 1769-1772.
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This e-pub was written by Eileen K. Corrigan of NIDDK's Office of Health Research Reports. The draft was reviewed by Dr. George P Chrousos, National Institute of Child Health and Human Development, Dr. Judith Fradkin, National Institute of Diabetes and Digestive and Kidney Diseases, and by Dr. Richard Horton, University of Southern California Medical Center.
This e-text is not copyrighted. NIDDK encourages users to duplicate and distribute as many copies as needed. Printed single copies may be obtained from the Office of Communications and Public Liaison, NIDDK, 31 CENTER DRIVE, MSC 2560, Bethesda, Maryland 20892-2560.
e-text posted: 12 February 1998
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