Pituitary-ovarian function in normal women during the menopausal transition

The excretion of follicle stimulating hormone (FSH), luteinizing hormone (LH), oestrogens and pregnanediol was measured in weekly urine samples collected for 14-87 weeks (median, 43 weeks) from thirty-one perimenopausal women aged 36-55 years (median, 50 years). The results were compared with those found in twenty-two postmenopausal women aged 55.4 +/- 5.4 years (mean +/- SD), and in twenty premenopausal women aged 44.4 +/- 3.4 years with regular, ovulatory, menstrual cycles. Women classed as perimenopausal had a recent history of irregular menstrual cycles following regular cyclicity. The hormone patterns observed in the perimenopausal women varied widely, both between individuals and from time to time in the same individual. They ranged from ovulatory cycles with low premenopausal levels of FSH, to transient episodes indistinguishable from those found in postmenopausal women with high levels of FSH and LH. Between these extremes were patterns rarely seen at other times in reproductive life: namely, (1) in fourteen women on thirty-two occasions lasting 2-9 weeks, postmenopausal levels of FSH and LH occurred in association with high oestrogen levels; (2) in eighteen women on thirty occasions lasting 2-8 weeks, there was an elevation of LH (but not FSH) into the postmenopausal range; (3) in thirteen women on twenty-six occasions lasting 1-2 weeks, there was an elevation of FSH (but not LH) into the postmenopausal range. These patterns were not seen in any of the premenopausal women. Typically, the approach of the menopause was marked by an increased incidence of high postmenopausal levels of FSH and LH. Ovulatory cycles were observed at all stages in the perimenopause, and occurred within 16 weeks of the last menstrual period in seven of the thirteen women who became postmenopausal during the study. It is concluded that the appearance of high levels of FSH and LH is characteristic of the perimenopause and often precedes the sustained loss of sex hormone secretion by the ageing ovary. Postmenopausal biochemical parameters are no guarantee of the postmenopausal state.