An abnormal early evening peak of plasma prolactin in nulliparous and obese post‐menopausal women

Abstract

Plasma specimens were obtained in the afternoon (13.30-17.29 h) for 668 post-menopausal women and in the evening (17.30-20.30 h) from another 219 women. The mean evening plasma prolactin level was significantly higher than that found in the afternoon (P < 0.0007). Mean afternoon prolactin levels were not related to nulliparity and body weight. In nulliparous obese women, the mean of the evening peak prolactin concentrations was double that of comparable women studied in the afternoon (P < 0.003). Abnormal cyclic prolactin levels are related to breast cancer predisposition.