Acromegaly

Summary

Acromegaly is a chronic debilitating disease caused by growth hormone (GH) hypersecretion, usually from a pituitary adenoma. It is frequently diagnosed after many years of active GH hypersecretion, and causes significant morbidity and mortality due to cardiac, pulmonary and musculoskeletal changes. Local complications resulting from the pituitary tumour can also occur. The most important feature that will enable a physician to diagnosis the disease is clinical vigilance. Measurement of elevated plasma mecasermin (insulin-like growth factor I, IGF-I) is the single best test to make the diagnosis. Once the diagnosis is confirmed, a GH-secreting tumour should be sought, by performing a careful magnetic resonance imaging or computed tomography scan of the pituitary gland and hypothalamus.

Therapy is directed at both preventing local complications of the tumour mass as well as normalising GH secretion. Surgical resection of the tumour is almost always the first step in treatment. If GH secretion is not normalised, which is best assessed by determining whether plasma IGF-I returns to the normal range, further treatment with radiation and/or medical therapy is required. Bromocriptine normalises GH in approximately 10% of patients and causes pituitary shrinkage in a similar fraction of patients. Octreotide is considerably more expensive than bromocriptine and is given subcutaneously, but is more effective in both normalising GH secretion and in shrinking tumours. Octreotide treatment of the pituitary tumours prior to surgical resection may be of value, but requires further investigation.