Bromocriptine reduces growth hormone in acromegaly.

We assessed serum growth hormone (GH) levels in ten patients with acromegaly during a 24-hour profile and a 75-g oral glucose tolerance test (GTT). Serum GH levels were measured after five weeks of bromocriptine mesylate therapy, 20 mg daily (P1), after five weeks without bromocriptine mesylate therapy (P2), and again five weeks following restarting treatment with bromocriptine, 20 mg daily (P3). During the 24-hour profile, the following occurred: (1) mean serum GH level of the group was lower during P1 (20.5 mU/L) and P3 (20.8 mU/L) than P2 (49.6 mU/L); (2) in six individual patients during P1 and P3, there was a significant reduction in the mean serum GH value; and (3) a marked circadian variation in the serum GH value was present both with and without the drug therapy in five patients. During the GTT, the mean serum GH value was lower during P1 (18.4 mU/L) and P3 (16.7 mU/L) than P2 (43.3 mU/L), and in seven individual patients during P1 and P3, there was a significant reduction in the mean serum GH value. Overall, a clear reduction in serum GH values due to bromocriptine was demonstrated. In individual patients, serum GH values during a 24-hour profile and GTT gave similar indications of response.