Predicting the menopause: the role of inhibin B

he menopause is defined as the spontaneous cessationof menses resulting from the loss of ovarian follicularactivity. Making the diagnosis that a woman is post-menopausal is generally straightforward based on the com-bination of amenorrhoea and blood hormone analysisshowing high follicle-stimulating hormone (FSH) and lowoestradiol concentrations. What can be more difficult isdefining what is going on in the lead up to the menopause,when hormone tests can give very variable results. It is moredifficult still to predict when a woman will becomemenopausal, for example when there is a family history ofpremature menopause or when a woman has previouslyhad chemotherapy for a malignancy. The essential concept is that the ovary is endowed witha finite number of follicles, each containing an oocyte;this number declines with time. Primordial follicles areformed before birth, and thereafter a number of folliclesstart growing every day. The number of follicles that startto grow each day is believed to reflect the total numberpresent,