Estradiol and testosterone levels are lower after oophorectomy than after natural menopause.

Objective: The aim of this study was to compare hormone levels between women who became postmenopausal after a prophylactic bilateral salpingo-oophorectomy, and women who became postmenopausal in a natural way.

Methods: In this cross-sectional study, we investigated estradiol, testosterone, SHBG, IGF-1 and IGFBP-3 levels in 35 surgically and 40 naturally postmenopausal women.

Results: Serum samples were drawn at a mean age of 45.9 years for women with surgical menopause and at 56.5 years for women with natural menopause. Mean estradiol levels declined 1.4 pmol/l per year in both menopausal groups, however, at an 11.1 pmol/l lower level for women with surgical menopause. Testosterone levels of naturally postmenopausal women remained stable at a level of 0.89 nmol/l, while testosterone levels of the surgically postmenopausal women declined 0.04 nmol/l per year.

Conclusions: For IGF-1, IGFBP-3 and SHBG, no differences were found between surgically and naturally postmenopausal women. Lower estradiol levels of surgically as compared to naturally postmenopausal women seem to be fully explained by the earlier onset of menopause in combination with the same age-related decrease. However, a decrease in testosterone levels seems to occur in oophorectomized women only, suggesting postmenopausal activity of ovaries in situ.