CIRCULATING LEVELS OF PROLACTIN DURING THE MENSTRUAL CYCLE

Abstract

SUMMARY In detailed studies on seventeen volunteers, it has been shown that changes in prolactin levels during the menstrual cycle are irregular and inconsistent. Some, but not all, subjects have elevated levels at mid‐cycle, and higher levels in the luteal phase than in the follicular phase. At all stages of the cycle, prolactin levels may show short‐term random fluctuations of as much as 110%. There was no apparent relation between levels of prolactin and those of LH, FSH, oestradiol‐17β or progesterone. It is suggested that if prolactin has any role in the control of the menstrual cycle, then the normal circulating levels are considerably in excess of the threshold requirements for its action.