The pathology of growth hormone excess or acromegaly lies in the pituitary (1). Acromegaly is mostly caused by an adenoma of the growth hormone producing cells in the pituitary. In children, GH excess leads to extreme large posture (gigantism), in adults, growth of hands, feet, face and organs is more common. GH acts both directly at peripheral tissues and indirectly,
through induction and secretion of IGF-1 by the liver. Surgery or radiation therapy are used to treat growth hormone secreting tumors. Octreotide, an analogue of the hormone somatostatin, which inhibits GH secretion, is also useful in the treatment of acromegaly. Dopamine agonists can sometimes be used to suppress GH secretion.
I. Insulin-like growth factor-1 (IGF-1) levels are decreased in acromegaly. II. Increased GHRH levels in the hypothalamus can cause GH excess.
Extra info: As a result of increased GH levels in acromegaly, also plasma IGF-I levels (secreted by the liver) are increased. Increased levels of GHRH (growth hormone releasing hormone) in the hypothalamus stimulate the growth hormone cells to release more GH.