Variation of urinary follicle-stimulating hormone level after menopause : From the results of Japan Nurses' Health Study

The change in follicle-stimulating hormone (FSH) during the menopausal transition and associations of FSH with various diseases have been assessed by using blood samples. We examined cross-sectionally the variation of FSH levels, associations of estrone and estradiol with FSH, and associations of BMI with these hormones by using urinary samples from peri- and postmenopausal women in Japan. Of 4472 participants in the Urinary Isoflavone Concentration Survey of the Japan Nurses' Health Study, we analyzed urinary levels of estrone, estradiol and FSH in 547 women aged from 45 to 54 years. Urinary FSH levels varied widely in postmenopausal women and the pattern of change in urinary FSH levels seems to be similar to that in blood FSH levels in previous studies. There were no significant differences in age, body mass index (BMI), estradiol, estrone and estradiol/estrone ratio among three groups according to the tertile of FSH. In postmenopausal women, there were significant associations of BMI with levels of estrone and estradiol, but there was no significant association of BMI with FSH. Studies using urinary samples will allow us to establish a study project as a large-scale population-based study to determine associations between FSH and various diseases after menopause.