Diagnostic role of follicle-stimulating hormone (FSH) measurements during the menopausal transition--an analysis of FSH, oestradiol and inhibin.

This review examines the role of follicle-stimulating hormone (FSH) measurement in assessing the significance of symptoms and possible continuing fertility during the menopausal transition. Follicle-stimulating hormone measurement is advocated frequently as a useful diagnostic tool in perimenopausal patients. Several investigators have shown that the serum FSH level increases in the early--mid-follicular and early postovulatory phases in women over the age of 40 years who continue to experience regular menstrual cycles. The serum oestradiol level may fall (although this is controversial) and the immunoreactive inhibin level falls, being inversely correlated with the rising FSH level. When alterations in menstrual cyclicity or flow commence, signalling the onset of the menopausal transition, FSH levels may change abruptly, rising into the normal postmenopausal range and falling again into the range normally seen in young fertile women. Oestradiol and inhibin generally fluctuate in parallel with each other but inversely to FSH, although at times oestradiol in particular may be increased markedly. Postmenopausal FSH levels may be followed by endocrine evidence compatible with normal ovulation. After the menopause, FSH levels rise 10-15-fold, with low oestradiol and undetectable inhibin levels. It is concluded that FSH measurement is of little value, if any in the assessment of women during the menopausal transition because it cannot be interpreted reliably and because, apparently, ovulatory (and, presumably, potentially fertile) cycles may occur subsequent to the observation of postmenopausal FSH levels. Both oestradiol and inhibin are important negative feedback regulators of circulating FSH.