Changes in plasma GH levels and clinical activity during bromocriptine therapy in acromegaly. The value of predictive tests.

Abstract

Twenty-seven patients with active acromegaly despite previous treatment by surgery and/or radiotherapy received bromocriptine in a dose of 10-20 mg daily for a period of 6-9 months. The results of chronic bromocriptine treatment were evaluated by measurement of plasma growth hormone (GH) levels during the day and by subjective and objective criteria of clinical activity. The results of chronic bromocriptine treatment were also compared with four biochemical criteria obtained before treatment e.g. basal plasma prolactin (Prl) levels and the plasma GH response to oral administration of 2.5 mg bromocriptine respectively iv administration of 200 micrograms TRH and 500 micrograms somatostatin. The main observations may be summarized as follows: 1) The mean pre-treatment GH levels during the day ranged from 6-207 mU/1. Hyperprolactinaemia was present in 6 patients. 2) During bromocriptine treatment mean plasma GH levels decreased to less than 50% in 11 patients (GH responders) whereas in 19 patients changes of mean plasma GH and of subjective criteria of clinical activity were concordant. 3) Glucose tolerance improved significantly (P less than 0.01) in 10 GH-responders and the urinary hydroxyproline/creatinine ratio decreased significantly (P less than 0.05) in 8 GH-responders. 4) Five out of 6 patients with hyperprolactinaemia belonged to the group of GH-responders. 5) A single dose of 2.5 mg bromocriptine induced a more than 50% decrease of plasma GH in 8 of 11 GH-responders and in 5 of 16 GH non-responders.(ABSTRACT TRUNCATED AT 250 WORDS)