Effect of endogenous estradiol levels on bone resorption and bone mineral density in healthy postmenopausal women: a prospective study.

OBJECTIVE

To investigate the effect of endogenous estrogens on bone mineral density (BMD) and bone markers in postmenopausal women over 24 months.

METHODS

Fifty out of 99 postmenopausal women seen previously were re-assessed after 24 months. Levels of BMD, bone markers, serum estradiol (E(2)) and total testosterone were determined.

RESULTS

BMD decreased in the femoral neck ( approximately 2%) (p < 0.008), but remained stable in the other skeletal areas; E(2) and serum Crosslaps (sCTX) decreased by 34% (p < 0.001) and 21% (p < 0.003), respectively. Women aged < or = 65 years exhibited decreased BMD only in the femoral neck (2%, p < 0.01), without changes in bone markers. Women aged > 65 years exhibited a decrease in sCTX levels and stable BMD values at all skeletal sites. E(2) levels decreased similarly in both groups ( approximately 35%). Women with baseline E(2) levels > or = 10 pg/ml showed stable BMD in spite of their E(2) levels decreasing by 42% (p < 0.001); sCTX decreased by 21% (p < 0.01). Women with baseline E(2) levels < 10 pg/ml showed a 2% decrease (p < 0.001) in femoral neck BMD and a 19% decrease (p < 0.002) in E(2) levels, without changes in bone markers.

CONCLUSION

Although endogenous E(2) decreased to around 7 pg/ml in these menopausal women, this level would seem to be sufficient to maintain BMD in almost all skeletal areas, and to be more effective in older women.