The Menopausal Transition: Analysis of LH, FSH, Estradiol, and Progesterone Concentrations During Menstrual Cycles of Older Women

TLDR

Large population studies show that intermenstrual interval variability markedly increases just before menopause. This study compared LH, FSH, estradiol, and progesterone levels across menstrual cycles in perimenopausal women to those in young normal women. The authors followed 2 women over 2 years, documenting 14 variable‑length cycles during the menopausal transition. Perimenopausal women exhibited shorter cycles with lower estradiol, markedly elevated FSH while LH remained normal, and variable cycles were linked to either follicular maturation with diminished estrogen/progesterone or anovulatory bleeding, underscoring independent pituitary regulation of LH and FSH.

Abstract

Studies of menstrual cycle length in large populations demonstrated that there is a striking increase in the variability of intermenstrual intervals just before menopause. The changes in serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone (P) during menstrual cycles in a group of perimenopausal women were compared with the findings in young normal women. In 8 women, 46–56 years old with regular cycles, cycle length was shorter and the mean E2 concentration was lower than in younger women. There was a striking increase in FSH concentration throughout the cycle while LH remained in the normal range. In 2 women, 14 cycles of variable length were studied during 2 years of the menopausal transition. In some instances, hormonal changes associated with follicular maturation and corpus luteum function occurred in the presence of high, menopausal levels of LH and FSH with a diminished secretion of E2 and P. In others vaginal bleeding occurred during a fall in serum E2 with no associated rise in P. Cycles of variable length during the menopausal transition may be due either to irregular maturation of residual follicles with diminished responsiveness to gonadotropin stimulation, or to anovulatory vaginal bleeding that may follow estrogen withdrawal without evidence of corpus luteum function. The observation of elevated FSH concentrations and normal LH levels in perimenopausal women emphasizes the complexity of the hypothalamicpituitary-ovarian regulatory system and suggests that LH and FSH are modulated independently at the level of the pituitary.