Serum Androstenedione and Testosterone Levels During the Menstrual Cycle

Utilizing specific radioimmunoassays serum androstenedione, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) were measured daily in the same aliquots of sera in 6 ovulatory menstrual cycles. In 3 of 6 cycles a progressive increase in serum androstenedione concentration was seen during the follicular phase. The mean androstenedione level during the middle third of the menstrual cycle was significantly higher than during the earlier (p < 0.01) or later (p < 0.001) portions. Serum testosterone levels in the same individual cycles showed random variations. Again the mean T level was significantly higher (p < 0.001) during the middle third as compared to either the beginning or end of the menstrual cycle.