Acromegaly is the abnormal enlargement of limbs and facial features as a result of hypersecretion of growth hormone after maturity. The disease is usually the result of a pituitary tumor.

The incidence of acromegaly is estimated to be 3:1,000,000 to 4:1,000,000.

More than 95% of growth hormone–releasing hormone (GHRH) independent cases of acromegaly are the result of growth hormone (GH)–secreting pituitary adenoma. These adenomas are either macroadenomas (>1 cm) or microadenomas (<1 cm). Macroadenomas predominate, accounting for more than 80% of the tumors.