Addison's disease

From New World Encyclopedia

Addison's disease is the hyposecretion of all adrenal steroid hormones. It usually follows the autoimmune destruction of the adrenal cortex (outer layer of the adrenal gland) in which the immune system creates antibodies against the body's own tissues. Inherited disorders in which defective enzymes for adrenal steroid production are produced are often marked by excess androgen (sex steroid) secretion. This is because substrates that cannot be made into cortisol or aldosterone are converted to androgens (sex steroids).

Hyposecretion pathologies are far less common than Cushing's syndrome.

Addison's disease, also known as chronic adrenal insufficiency, or hypocortisolism, is a rare endocrine or hormonal disorder. It occurs in all age groups and afflicts men and women equally. The disease was first described by the British physician Dr. Thomas Addison in his 1849 publication: On the Constitutional and Local Effects of Disease of the Suprarenal Capsules.

It is estimated that the disease affects about 1 to 2 per 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 anterior pituitary gland does not produce enough adrenocorticotropic hormone (ACTH) to adequately stimulate the adrenal glands.

Signs and symptoms

Early signs

Addison's disease progresses slowly and symptoms may not present or be noticed until some stressful illness or situation occurs. Common symptoms are:

  • Chronic physical fatigue that gradually worsens
  • Muscle weakness
  • Loss of appetite
  • Weight loss
  • Nausea/vomiting
  • Diarrhea
  • Low blood pressure that falls further when standing (orthostatic hypotension)
  • Areas of hyperpigmentation (darkened skin), known as melasma suprarenale
  • Irritability
  • Depression
  • Craving for salt and salty foods
  • Hypoglycemia, or low blood glucose levels, which are worse in children
  • For women, menstrual periods that become irregular or cease
  • Tetany (particularly after drinking milk) due to excess phosphate
  • Numbness of the extremities, sometimes with paralysis, due to potassium excess
  • Eosinophilia (an increased number of eosinophils, which are white blood cells that play a major role in allergeric reactions)
  • Polyuria (increased urine output)

Addisonian crisis

An illness or accident can aggravate the adrenal problems and cause an Addisonian crisis, also known as acute adrenal insufficiency; however, the most common cause is discontinuing corticosteroid therapy without tapering the dose. Symptoms that may occur include:

  • Brown coating on tongue and teeth due to hemolyis, or iron loss
  • Sudden penetrating pain in the legs, lower back, and/ or abdomen
  • Severe vomiting and diarrhea, resulting in dehydration
  • Low blood pressure
  • Loss of consciousness
  • Hypoglycemia

If left untreated, an Addisonian crisis can be fatal. It is considered a medical emergency.

Diagnosis

In suspected cases of Addison's disease, low adrenal hormone levels must be demonstated after appropriate stimulation with synthetic pituitary hormone.

Once demonstrated, the cause of adrenal failure needs to be elucidated. The most common cause of Addison's disease is autoimmune and occurs when the body's immune system creates antibodies against the body's own tissues. It can be tested for with an assay for 21-hydroxylase antibodies. If no antibodies are present, an autoimmune cause can be eliminated and infectious or genetic causes ought to be sought. These may include imaging of the adrenal glands, tests for tuberculosis or HIV infection, and searching for metastatic cancer.

Etiology

Seventy percent of cases of Addison's disease are said to be due to autoantibodies directed against adrenal cells containing 21-hydroxylase, an enzyme involved in the production of cortisol and aldosterone. Adrenal insufficiency occurs when at least 90% of the adrenal cortex has been destroyed. As a result, often both glucocorticoid (cortisol) and mineralocorticoid (aldostertone) 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 syndrome is classified into two separate forms, type I and type II. In type I, which occurs in children, the adrenal insufficiency may be accompanied by underactive parathyroid glands (hypothyroidism), slow sexual development, pernicious anemia, chronic candida infections, chronic active hepatitis, and alopecia (hair loss). Type II features include an hypothyroidism, slow sexual development, diabetes (type I), and vitiligo, which is the loss of pigment from various areas of the skin. Type II tends to afflict young adults and is often called Schmidt's syndrome.

Twenty percent of cases of Addison's disease and primary adrenal insufficiency are due to tuberculosis, or TB. Although TB was a major cause of the disease in the nineteenth century when Addison's disease was first discovered, its role has decreased remarkably due to better treatment for TB.

The remainder of cases are due to HIV, sarcoidosis (a disease characterized by the formation of granulomatous lesions that appear especially in the liver, lungs, skin, and lymph nodes; also called sarcoid), amyloidosis (a disorder marked by the deposition of amyloid in various organs and tissues of the body; may be associated with a chronic disease such as rheumatoid arthritis, tuberculosis, or multiple myeloma), hemochromatosis, metastatic cancer to the adrenal glands, adrenal hemorrhage (profuse bleeding), Waterhouse-Friderichsen syndrome (massive, usually bilateral, hemorrhage into the adrenal glands caused by fulminant meningococcemia), and congenital adrenal hyperplasia.

Treatment

Treatment for Addison's disease involves replacing the lacking cortisol and, if necessary, fludrocortisone as a replacement for the missing aldosterone. Caution must be exercised when a person with Addison's disease faces a stressful situation, such as surgery or pregnancy.

Famous patients

A famous sufferer of Addison's Disease was President John F. Kennedy. Jane Austen is thought to have been another, although the disease had not been described during her lifetime.

In animals

Addison' disease is rare in dogs, but it has been diagnosed in Bearded Collies and Chihuahuas and in rare cases in Standard Poodles. In dogs it is inherited via the female line, possibly due to autoimmune antibodies in the milk.

The first sign of Addison's Disease in dogs is a much longer urinating period than normal. Urine is very light and pressure while urinating is lower than usual. When the dog loses its appetite and changes its temperament, a blood test should be taken as soon as possible.

Addison's disease is treated with Prednisolone and Florinef, which are taken twice a day after meals. The medications increase thirst and water input as well as increase urine output. An alternative to oral Florinef is a monthly injection called Percorten V, whose active ingredient is desoxycorticosterone pivalate, or DOCP. The amounts of the medicines taken depend on the weight of the individual dog. Blood samples need to be taken after every 3-4 months, regardless of how the dog feels, to make sure the dog's condition is stable.

Stress levels, both positive and negative, of an ill dog must be kept to a minimum. A dog's relaxing pulse reading should be known so that a stressful event can be identified by an increased pulse reading. If an owner of an ill dog knows about an upcoming stressful situation, such as a show or traveling, he/ she can give a larger does of medicine.

References
ISBN links support NWE through referral fees

Addison T. On the constitutional and local effects of disease of the suprarenal capsules. London: P. Highley, 1855. An exact reprint with colour images is available via the external link below.

Silverthorn, D. 2004. Human Physiology, An Integrated Approach (3rd Edition). San Francisco: Benjamin Cummings. ISBN 013102153

See also

External Links

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.