Plasma growth hormone suppressive effect of bromocriptine in acromegaly. Evaluation by plasma GH day profiles and plasma GH concentrations during oral glucose tolerance tests.

In most studies reporting favourable results of chronic bromocriptine treatment in acromegaly, plasma GH levels are measured at fixed intervals during the day. Negative results are reported in one major study measuring plasma GH levels during oral glucose tolerance tests (Lindholm et al., 1981). This study does not mention the time interval between the last dose of bromocriptine and the performance of an OGTT, but due to the short duration of action of bromocriptine this may be critical. Therefore, in the present report the plasma GH suppressive effect of bromocriptine in acromegaly is studied using plasma GH day-profiles as well as OGTT's during continued bromocriptine administration and OGTT's at two different time intervals after the last dose of bromocriptine. Twelve patients with clinically active acromegaly were treated with 10-20 mg bromocriptine for 6-9 months. After 6-9 months during continued bromocriptine administration the plasma GH suppressive effect of bromocriptine was evaluated by the mean of four plasma GH determinations during the day and by the mean of seven plasma determinations during oral glucose tolerance tests (OGTT's) performed 1 h, 10 h and 34 h after the last dose. The percentage decrease of the mean plasma GH level during the day induced by chronic bromocriptine treatment showed a good correlation (r = 0.86, P less than 0.001) with the percentage decrease of the mean plasma GH level during OGTT, if the post-treatment test was carried out one hour after the last dose of bromocriptine.(ABSTRACT TRUNCATED AT 250 WORDS)