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This prospective study includes 31 women with a prolactin (PRL) level greater than 20 ng/ml (upper limits of normal in our laboratory) on at least three different occasions and chemically euthyroid. Each woman received bromocriptine mesylate (BRC) 1.25 mg (1/2 tablet)/day for 2 weeks, at which time a repeat PRL level was obtained. If needed, the dose was increased in a stepwise fashion until the PRL level was in the normal range. Results show that 12 of 15 patients with an initial PRL greater than 20 but less than 50 ng/ml required 2.5 mg or less of BRC daily. Of 9 patients with a PRL greater than 50 but less than 100 ng/ml, 5 required 2.5 mg daily with the remaining 4 needing 5.0 mg. Five of 7 patients with a PRL greater than 100 ng/ml required 5.0 mg or more, while one responded to 1.25 mg. These findings confirm that a lower than manufacturer-recommended dose of BRC is usually effective in normalizing PRL levels, especially when the initial PRL is less than 100 ng/ml.

We have shown that a smaller dose of bromocriptine is effective in lowering the PRL level to the normal range in some hyperprolactinemic women. Based on these findings, we recommend that when treating hyperprolactinemic women who desire conception, the dose of bromocriptine should be titrated according to the response of circulating PRL levels. This will minimize the dose, reduce cost, probably reduce side effects, and possibly avoid undesirable functional effects such as corpus luteum dysfunction.