RESPONSE OF ACROMEGALY TO LONG TERM BROMOCRIPTINE THERAPY: A BIOCHEMICAL AND CLINICAL ASSESSMENT

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Abstract
The long term effects of bromocriptine in 12 acromegalics treated for a mean duration of 10.2 mo. are reported. Seven showed a significant (P < 0.05) and sustained fall in serum immunoreactive growth hormone (GH) levels throughout 24 h, 6 of whom had a 50% or greater reduction in mean circulating GH during glucose tolerance testing [GTT]. Only 1 patient had mean serum GH levels throughout the day suppressed to normal (< 5 mIU/l) but 3 had suppression of mean serum GH during GTT to normal or very near normal (< 10 mIU/l). The effective dose was 20 mg daily. Only 4 patients reported any improvement in soft tissue swelling and acral features, which was unrelated to the GH response. Possible reasons for the discrepancy between clinical and biochemical responses are discussed. In 9 patients bromocriptine was discontinued and pituitary ablative therapy offered. Three of 4 patients who underwent trans-sphenoidal hypophysectomy had mean GH levels during GTT reduced to < 7 mIU/l. In the 3 who continued bromocriptine treatment GH suppression was maintained at less than 10 mIU/l for up to 3 yr but with little change in acral features. Although bromocriptine is safe and was well tolerated it is not as effective as existing forms of pituitary ablative therapy and should be reserved for those cases where ablation is contraindicated or unsuccessful.