Bromocriptine therapy in acromegaly: effects on plasma GH levels, somatomedin-C levels and clinical activity.

Thirty-one patients with active acromegaly were treated with 10-20 mg bromocriptine daily for a period of 6-9 months. The clinical response was evaluated both by a subjective 'score of symptoms', and by a combined subjective and objective 'clinical and metabolic improvement score' (c-m score). The biochemical response was evaluated both by measurement of the mean of four plasma growth hormone (GH) determinations during the day and by measurement of plasma somatomedin-C (Sm-C) concentration. The clinical response as assessed by both methods showed a better correlation with changes in plasma GH levels (respectively r = 0.33; r = 0.50) than with changes in Sm-C levels (r = 0.20; r = 0.36). The study confirms that in some patients clinical improvement is not accompanied by a decrease of plasma GH concentration. However, it is not possible to identify a subgroup of patients who showed clinical improvement with a decrease of Sm-C levels, but whose plasma GH levels remained constant. It is concluded that measurement of plasma GH levels still appears to be the most useful biochemical assessment of disease activity in bromocriptine-treated acromegaly.