Regulation of Human Gonadotropins: IV. Correlation of Serum Concentrations of Follicle Stimulating and Luteinizing Hormones During the Menstrual Cycle1

Abstract

Serum concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) have been measured by radioimmunoassay throughout 37 menstrual cycles in 37 women. Concentrations of LH and FSH each rose sharply on the first day of menses and remained quite constant until shortly before the middle of the cycle. Concentrations of LH and, to a variable extent, FSH, rose sharply at midcycle with the peak in LH beginning before and lasting longer (1½ to 2 days) than that of FSH. Following the peak, concentrations of LH were generally lower than those in the follicular phase of the cycle and were quite variable, with occasional minor peaks. During the luteal phase of the cycle, concentrations of FSH progressively decreased to a mean level approximately half that seen during the follicular phase of the cycle and little daily variation was seen. Diurnal rhythms in concentration of LH and, to a lesser extent, FSH, were found during the follicular phase of the cycle.