Effect of treatment with bromocriptine on the size and activity of prolactin producing pituitary tumours

Eleven consecutive patients with large prolactinomas were treated for 6 months with bromocriptine, (7.5 mg/day). Nine had invasion of the sphenoidal sinus, one a visual field defect and one a secondary trigeminal neuralgia. At the end of the treatment period 8 of the first 9 patients showed radiographical signs of bone remodelling and/or actual reduction of the tumour size. The last 2 patients had complete disappearance of their symptoms. The remissions could be observed as early as 3 weeks after the start of the treatment. Two patients suffered acute, reversible (partial in one case) episodes of loss of vision during the study. During the treatment the prolactin values decreased in all patients to an average of 1.7% of the baseline levels. There was a steep rise in the serum prolactin concentrations after withdrawal of the drug. After one month there was a plateauing at a high level, although lower than basal level. Libido and potency were restored in all 3 males studied. Two of the females experienced orgasm for the first time in their lives after some years of primary frigidity. It is concluded that bromocriptine reproducibly reduces the size of prolactinomas. This effect can be observed shortly after the beginning of the treatment and is at least partially reversible. Episodes of pituitary apoplexy may occur during the treatment of large tumours despite an otherwise favourable response.