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: