Bromocriptine treatment of acromegaly

Bromocriptine at a dose of 7.5-30 mg/day was given to 12 acromegalics for 6 mo. Mean serum growth hormone (GH) levels during a glucose tolerance test (GTT) were significantly lowered by the drug. In four patients the serum GH response during a GTT was suppressed to normal (i.e. less than or equal to 5 mlU/liter). If bromocriptine had not brought the serum GH response to a GTT to normal at a dose of 20 mg/day, this effect was not achieved by raising the dose to 30 mg/day. Bromocriptine was effective for the duration of treatment. On discontinuing therapy there was an increase in serum GH levels. No obvious clinical changes in the acromegalic features were noted. One patient with impaired glucose tolerance and one with established diabetes had normal glucose tolerance while on bromocriptine and another two patients with impaired glucose tolerance showed no obvious changes while on the drug. Side effects were minor. X-rays of the pituitary fossa before starting and at the end of treatment showed no significant change. We conclude that although bromocriptine is the most promising form of medical treatment for acromegaly to date, it is fully effective only in a minority of patients.