Acromegaly is a rare but serious condition caused by too much growth hormone (GH) in the blood. GH is released into the bloodstream by the pituitary gland, located at the base of the brain. The blood carries GH to other parts of the body where it has specific effects. In children, GH stimulates growth and development. In adults, GH affects energy levels, muscle strength, bone health, and one’s sense of well-being.
Too much GH in children is called gigantism and is extremely rare. Acromegaly in adults occurs mainly in middle-aged men and women.
Acromegaly is usually caused by a non-cancerous tumor in the pituitary gland called a pituitary adenoma. The tumor produces too much GH and raises the level of GH in the blood. Too much GH also raises the level of insulin-like growth factor-1 (IGF-1), a hormone produced in the liver that also promotes growth. Rarely, acromegaly is caused by hormone-producing tumors in other parts of the body.
If acromegaly is suspected, your doctor will do a blood test to check your level of IGF-1. High IGF-1 levels can mean that your levels of GH are also high.
Another way to diagnose acromegaly is with an oral glucose tolerance test. In this test, GH levels in the blood are measured after you drink sugar water. Normally, the sugar water will make the pituitary gland stop producing GH and blood levels drop. However, a GH-producing pituitary tumor will not stop making GH, so the levels of GH in the blood will not change.