Long-term treatment of hyperprolactinaemia with bromocriptine: effect of drug withdrawal.

Fifty-one patients with hyperprolactinaemia (23 with macroadenoma, 23 with microadenoma, and five with idiopathic hyperprolactinaemia) were treated with bromocriptine for 2-12 years (4.9 +/- 2.9 years, mean +/- SD). During therapy, the serum PRL levels were suppressed into the normal range in all but five patients. In these five patients, despite the high circulating PRL, gonadal function returned to normal in three, while in the other two gonadotrophin reserve was impaired even before therapy. Gel chromatography showed that one of these patients had a high proportion of a large molecular weight form of PRL. Twenty-four patients received bromocriptine as the sole method of treatment for over 2 years (3.4 +/- 2.3 years). In five out of the 24 subjects (21%), serum PRL remained normal with no clinical symptoms after prolonged drug withdrawal (1-4 years). Twenty-one patients received radiotherapy in conjunction with bromocriptine therapy. Of these 11 had prior surgery. After a follow-up of 6.0 +/- 3.0 years after radiotherapy, serum PRL remained within the normal range in 6 out of 21 subjects (29%), 1-4 years after bromocriptine withdrawal. One of the patients had impaired GH response to insulin hypoglycaemia developing after radiotherapy. We conclude that prolonged bromocriptine treatment is an effective treatment for prolactinomas.