Effect of intravenous pyridoxine on plasma prolactin in hyperprolactinemic subjects.

Intravenous pyridoxine has been reported to lower plasma PRL in normal subjects and in patients with the amenorrhea-galactorrhea syndrome. We tested the effect of pyridoxine (300-mg iv bolus) on plasma PRL in nine patients with hyperprolactinemia due to a variety of causes. There was no effect of pyridoxine on elevated plasma PRL in any of the nine hyperprolactinemic subjects. The potential utility of pyridoxine in the long term treatment of the galactorhea-amenorrhea syndrome will require further study.