Wide distribution of the serum dehydroepiandrosterone and sex steroid levels in postmenopausal women: role of the ovary?

OBJECTIVE

Because the exclusive source of sex steroids (at least estrogens) after menopause is recognized to be dehydroepiandrosterone (DHEA), this study examines the interindividual variability of serum DHEA and its metabolites as well as the contribution of the ovary to global sex steroid physiology in postmenopausal women.

METHODS

Serum levels of DHEA and 11 of its metabolites were measured by gas or liquid chromatography/mass spectrometry in 442 intact and 71 ovariectomized postmenopausal women aged 42 to 74 years.

RESULTS

With a mean ± SD concentration of 2.03 ± 1.33 ng/mL, serum DHEA in intact postmenopausal women is highly variable with 5th and 95th centiles at 0.55 and 4.34 ng/mL, respectively, for a 7.9-fold difference. A comparable variability is observed for the 11 metabolites of DHEA. The 22.3% higher serum DHEA in intact compared with ovariectomized women is accompanied by parallel differences for all the other steroids, thus indicating that all sex steroids originate from circulating DHEA in postmenopausal women with no direct secretion of active estrogens or androgens by the postmenopausal ovary.

CONCLUSIONS

The 7.9-fold difference between low and high serum DHEA levels provides an explanation for the lack of signs of hormone deficiency in some women, whereas most of them have symptoms or signs. The approximately 20% contribution of the ovary to the total pool of DHEA with no direct secretion of estrogens or androgens in the circulation could possibly explain the reported negative effect of oophorectomy on longevity, especially from coronary heart disease events.