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.