Acromegaly is caused by the pituitary gland overproducing growth hormone (GH) over time. The pituitary, a small gland situated at the base of your brain behind the bridge of your nose, produces a number of hormones. GH plays an important role in managing your physical growth.

When GH is secreted into your bloodstream, it triggers your liver to produce a hormone called insulin-like growth factor-I (IGF-I). In turn, IGF-I stimulates the growth of bones and other tissues. If your pituitary gland makes too much GH, excessive amounts of IGF-I can result. Too much IGF-I can cause abnormal growth of your soft tissues and skeleton and other signs and symptoms characteristic of acromegaly and gigantism.

In adults, a tumor is the most common cause of too much GH production:

  • Pituitary tumors. Most cases of acromegaly are caused by a noncancerous (benign) tumor (adenoma) of the pituitary gland. The tumor secretes excessive amounts of growth hormone, causing many of the signs and symptoms of acromegaly. Some of the symptoms of acromegaly, such as headaches and impaired vision, are due to the tumor mass pressing on nearby brain tissues.
  • Nonpituitary tumors. In a few people with acromegaly, tumors in other parts of the body, such as the lungs, pancreas or adrenal glands, cause the disorder. Sometimes, these tumors actually secrete GH. In other cases, the tumors produce a hormone called growth hormone-releasing hormone (GH-RH), which stimulates the pituitary to make more GH.
Feb. 05, 2013

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