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

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Abstract
Patients (27) 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 mo. 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 4 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, i.v. administration of 200 .mu.g TRH and 500 .mu.g somatostatin. Bromocriptine was effective as adjunctive therapy when active acromegaly persisted after treatment with surgery and/or radiotherapy. In general, a good correlation was found between GH responsiveness and subjective and objective criteria of clinical activity during bromocriptine treatment. Hyperprolactinemia predicted GH responsiveness to chronic bromocriptine treatment with high specificity. The combination of a bromocriptine test and a TRH test are of best predictive value with respect to the results of chronic bromocriptine therapy in normoprolactinemic acromegalics.