The endocrinology of the menopausal transition: a cross-sectional study of a population-based sample.

TLDR

The study measured serum FSH, estradiol, inhibin, testosterone, and sex hormone‑binding globulin in 380 women aged 45.6–56.9 yr and categorized them into five menstrual‑cycle groups based on changes in flow and frequency. Across the groups, FSH rose markedly—53 % higher in group IV and 253 % higher in group V—while estradiol and inhibin fell to 54 % and 53 % of group I levels, and women who remained amenorrheic had even higher FSH and lower estradiol and inhibin, indicating that rising FSH and falling estradiol and inhibin are the key endocrine shifts of the menopausal transition.

Abstract

In a study of the endocrinology of the perimenopausal years, levels of serum FSH, estradiol (E2), immunoreactive inhibin (INH), testosterone, and sex hormone-binding globulin were measured in a population-based sample of 380 women (mean age, 49.4 yr; range, 45.6-56.9 yr). Subjects were divided into women who reported continuing regular menstrual cycles (27%; group I), a change in menstrual flow without a change in frequency (23%; group II), a change in frequency but no change in flow (9%; group III), changes in both frequency and flow (28%; group IV), and at least 3 months since their last menstrual period (13%; group V). After adjusting for age and body mass index, the geometric mean FSH increased across menstrual groups and, compared with group I, was 53% higher in group IV (P < 0.0005) and 253% higher in group V (P < 0.0001). Age- and body mass index-adjusted geometric means for E2 and INH in group V were 54% and 53% of those in group 1, respectively (P < 0.005, P < 0.0001). Women in group V who did not have a menstrual period in the next year had higher FSH and lower E2 and INH levels than those who subsequently went on to have at least one more menstrual period (P < 0.05). FSH was negatively correlated with E2 (r = -0.30) and INH (r = -0.39), whereas INH was positively correlated with E2 (r = 0.45). We conclude that an increase in serum FSH and decreases in E2 and INH are the major endocrine changes associated cross-sectionally with the menopausal transition.