The diagnosis and treatment of acromegaly

Acromegaly is an endocrine disorder that affects multiple organ systems and increases mortality by 2 to 4 times that of the general population. Elevated growth hormone (GH) levels are the hallmark of acromegaly, but GH secretion is pulsatile and not an accurate marker of disease. IGF-I provides a reliable indication of overall GH secretion and is the single most reliable screening test for acromegaly. In addition, many of the somatotrophic effects of GH are mediated by IGF-I. The goals of treatment of acromegaly are to achieve biochemical control, stabilize or reduce tumor size, and maintain or recover pituitary function. Treatment options for acromegaly include surgery, radiation therapy, and drug therapy. Available medical therapies include somatostatin analogs and dopamine agonists. The advantages and limitations of these therapies are reviewed. A novel medical therapy is pegvisomant, a GH receptor antagonist that binds to GH receptors on the cell surface of target cells and blocks GH signal transduction and GH action. Unlike other medical therapies, effectiveness of pegvisomant is independent of receptor expression on pituitary tumors. Pegvisomant has been demonstrated to be highly effective in reducing IGF-I concentrations to normal levels and significantly improving signs and symptoms of acromegaly in up to 97% of treated patients. Therefore, pegvisomant is a promising new agent that offers significant advances in the treatment of acromegaly.