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Disease Background - Acromegaly
About Acromegaly
Acromegaly is a rare, chronic, and insidious hormonal disorder that occurs when the pituitary gland produces excess growth hormone (GH). It most commonly affects middle-aged adults and may lead to premature death.1,2 In less than 1% of patients, the excessive GH secretion that causes acromegaly can be due to hypothalamic or other nonpituitary, GH-secreting tumours.3
Diabetes mellitus, hypertension, and increased risk of cardiovascular disease are the most serious health consequences of acromegaly. In addition, patients with acromegaly are at an increased risk of developing colon polyps, which can become cancerous.1,4
The prevalence of acromegaly is approximately 60 cases per million, and the incidence is 3.3 new cases per million per year.1,2
The term acromegaly—from the Greek words for "extremities" (acro) and "great" (megaly)—was popularised by Pierre Marie in 1886, and reflects the fact that a key feature of the disease is abnormal enlargement of the face, hands,
and feet.1,5

Causes
Acromegaly is caused by prolonged overproduction of GH and excessive production of insulin-like growth factor-1 (IGF-1). In 97% of cases, the overproduction of GH is caused by a pituitary adenoma. The rate of GH production and the aggressiveness of the tumour vary from patient to patient.1,4
Most pituitary adenomas occur spontaneously from a genetic mutation in a single pituitary cell. The genetic mutation is not present at birth, but is acquired during life. A gene that regulates the transmission of chemical signals within pituitary cells acquires the mutation, leading to increased cell division and tumour formation.1
Other Tumours
Other rare causes of acromegaly include tumours of the pancreas, lungs, and adrenal glands. These tumours either produce GH themselves or, more frequently, they produce growth hormone-releasing hormone (GHRH), which stimulates the pituitary to make growth hormone, resulting in excessive levels of GH. In patients with these types of tumours, elevated levels of GHRH can be detected in the blood, ruling out pituitary defects as the cause of acromegaly.1,6
It is important to note that the pituitary gland may still be enlarged in patients with GHRH-producing, nonpituitary tumours, because this enlargement may be mistaken for a tumour. Careful analysis of all pituitary tumours removed from patients with acromegaly is important to prevent overlooking a tumour elsewhere in the body.1
Other Causes
Several rare hereditary syndromes also may cause acromegaly5:
- McCune-Albright syndrome
- Multiple endocrine neoplasia type 1 (MEN1)
- Familial acromegaly
- Carney syndrome
Read about the challenges of diagnosing acromegaly.
References: 1. National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, US Department of Health and Human Services. Acromegaly. Bethesda, MD: National Institutes of Health; 2008. NIH publication 08-3924. 2. Acromegaly Therapy Consensus Development Panel. Consensus statement: benefits versus risks of medical therapy for acromegaly. Am J Med. 1994;97:468-473. 3. Beuschlein F, Strasburger CJ, Siegerstetter V, et al. Acromegaly caused by secretion of growth hormone by a non-Hodgkin's lymphoma. N Engl J Med. 2000;342:1871-1876. 4. Jane JA Jr, Thapar K, Laws ER Jr. Acromegaly: historical perspectives and current therapy. J Neurooncol. 2001;54:129-137. 5. Ben-Shlomo A, Melmed S. Acromegaly. Endocrinol Metab Clin North Am. 2001;30:565-583. 6. Maugans TA, Coates MI. Diagnosis and treatment of acromegaly. Am Fam Physician. 1995;52:207-213.


