Effect of chronic metoclopramide therapy on serum pituitary hormone concentrations.

The effect of chronic (3--9 months) therapy with metoclopramide on serum levels of pituitary and thyroid hormones was studied in 4 males and 1 female. The mean serum prolactin concentration during metoclopramide therapy was significantly higher than after discontinuation of metoclopramide. Serum prolactin concentrations increased acutely after each dose of metoclopramide. Serum prolactin concentrations increased acutely after each dose of metoclopramide, and gradually returned to normal by 6--12 h. There was no sifgnificant differences in the serum TSH, T3, T4, GH, and gonadotrophin levels during and after metoclopramide administration. In the male subjects the mean serum testosterone was normal, but significantly lower during metoclopramide therapy.