Serum-prolatic in women with premenstrual syndrome.

Serum-prolactin was measured by radioimmunoassay during the menstrual cycle in 28 women who had the premenstrual syndrome (P.M.S.) and in a control group who did not have P.M.S. symptoms. Throughout the menstrual cycle mean serum-prolactin was signficantly higher in women with P.M.S. than in the controls. The average individual increase in serum-prolactin during the premenstrual period compared with the first 3 weeks of the cycle was also significantly higher in women with P.M.S. It is not clear whether the increase in serum-prolactin was merely an indicator of stress or was actually involved in producing some of the symptoms which constitute P.M.S.