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Acromegaly is a rare condition where the pituitary gland secretes too much growth hormone (GH), resulting in overproduction of insulin-like growth factor-1 (IGF-1) and excessive growth. Hormones are chemical substances produced by glands in the body that circulate in the blood and help control growth, metabolism, reproduction, and other functions. GH and IGF-1 are key hormones involved in the complex growth process. The pituitary gland secretes GH into the bloodstream; once it is in the bloodstream, GH triggers the liver to produce
IGF-1, which in turn directly stimulates bone and tissue growth.
The most common cause of acromegaly is a benign tumor of the pituitary gland. In rare cases, the condition can be caused by tumors in other parts of the body, such as the adrenal glands, lungs, or pancreas. Sometimes, these type of tumors can secrete GH, or they might produce another hormone (growth hormone-releasing hormone), which stimulates the pituitary gland to make more GH.
Approximately 15,000 people in the US and Canada are estimated to have acromegaly1, which is most commonly found in middle-aged adults. If the condition develops before bone growth is completed in adolescence, it is called gigantism.
Symptoms and Effects
The excessive growth associated with acromegaly occurs in the extremities where bones and soft tissues increase in size. The term acromegaly is derived from the Greek words “acro” (extremities) and "megaly" (enlargement). The most common signs and symptoms of this serious condition include:
- Enlarged hands, feet, and head
- Facial changes, such as bulging forehead, enlarged lower jaw, thickened lips, large tongue, wider spacing between teeth, distended nose
- Enlarged heart, kidney, liver, spleen, and other organs
- Fatigue, muscle weakness, and depression
- Extreme sweating and body odor
- Rough, oily, and thickened skin accompanied by coarse body hair
- Arthritis and joint pain, carpal tunnel syndrome
- Headaches and impaired vision
- Enlarged vocal chords and sinuses, resulting in a deeper voice
- Obstruction in the upper airway, leading to severe snoring, sleep apnea
- Enlarged, or “barrel,” chest • Impotence, decreased sexual drive
- Irregular menstrual cycle and lactation (breast milk production) in women
- Colon polyps
- Small outgrowths of skin tissue, or skin tags
Because it is an uncommon disorder with symptoms that develop gradually over time, acromegaly can be difficult to diagnose. Without treatment, the condition can lead to cardiovascular disease, hypertension, diabetes, and a possible increased risk of colon cancer.
If untreated, the mortality rate of people with acromegaly is at least two times higher,2 and the life expectancy is five to ten years less,3 than that of the general population. Treatments that control the excess production of growth hormone and IGF-1 can return the mortality rate in these patients to normal.4, 5
Treatment Options
Treatment options for acromegaly include surgical removal of the tumor, drug therapy, and radiation therapy of the pituitary gland. Depending on each individual case, a combination of these treatment options may be needed to manage the effects of acromegaly. For example, although surgery can be an effective treatment approach, in many cases, hormone levels may improve yet still not return to normal; these patients would need additional treatment, most commonly with drug therapy. Drug therapies include:
GH receptor antagonists, the most recent class of drugs developed to treat acromegaly, prevent GH from stimulating IGF-1 production by blocking the places on cells where growth hormone binds, or connects, with the GH receptor.
Somatostatin analogues operate like a naturally occurring hormone called somatostatin, which shuts off the production and secretion of GH.
Dopamine agonists promote the activity of dopamine, a chemical in the brain, to stop GH release by some pituitary tumors. These drugs generally do not work as well as the growth hormone receptor antagonists or the somatostatin analogues.
Radiation is usually reserved for patients who
1) can’t undergo surgery, or
2) whose tumor is not completely removed during surgery, or
3) who haven’t responded adequately to medication.
1 The National Institutes of Health cites an acromegaly prevalence of 40-60 per million
2 Orme SM et al. JCEM 83: 2730-4, 1998
3 Clayton RN et al. J Endocrinol (Suppl 1): S23-9, 1997
4 Abosch A et al. JCEM 83: 3411-8, 1998
5 Swearingen B et al. JCEM 83: 3419-26, 1998
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