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Alternative names Return to top
GiantismDefinition Return to top
Gigantism is an excessive secretion of growth hormone during childhood, before the closure of the bone growth plates. This excess growth hormone causes overgrowth of the long bones and very tall stature.Causes, incidence, and risk factors Return to top
The cause of excess growth hormone secretion is most often a benign pituitary gland tumor. Giantism may also be caused by an underlying medical condition such as multiple endocrine neoplasia type 1 (MEN-1), McCune-Albright syndrome (MAS), neurofibromatosis, or Carney complex.
If excessive secretion of growth hormone occurs after normal bone growth has stopped, the condition is known as acromegaly.
The vertical growth in height that marks this condition is also accompanied by growth in muscles and organs, which makes the child extremely large for his or her age. The disorder can also delay puberty.
Gigantism is very rare.
Symptoms Return to top
Signs and tests Return to top
Other hormone levels may be low due to damage to the pituitary, including thyroid hormone, testosterone (boys), estradiol (girls), or cortisol.
Treatment Return to top
In pituitary tumors with well-defined borders, surgery is the treatment of choice and is curative is about 80% of cases.
For situations in which surgery cannot completely remove the tumor, medication is the treatment of choice. The most effective medications are somatostatin analogs (such as octreotide or long-acting lanreotide), which reduce growth hormone secretion.
Dopamine agonists (bromocriptine mesylate, cabergoline) have also been used to reduce growth hormone secretion, but these are generally less effective. A medication that blocks the effect of growth hormone, pegvisomant, has recently become available.
Radiation therapy has also been used to normalize growth hormone levels. However, it can take 5-10 years for the full effects to be seen and is almost always associated with deficiencies in other pituitary homones. In addition, radiation has been associated with learning disabilities, obesity, and emotional changes in children. Most experts will use radiation only if surgery and medication fail.
Expectations (prognosis) Return to top
Pituitary surgery is usually successful in limiting growth hormone production.
Complications Return to top
Calling your health care provider Return to top
Call your health care provider if signs of excessive growth during childhood are present.
Update Date: 8/12/2004 Updated by: Aniket R. Sidhaye, M.D., Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |