PREMENOPAUSAL AND POSTMENOPAUSAL CHANGES IN BONE-MINERAL DENSITY OF THE PROXIMAL FEMUR MEASURED BY DUAL-ENERGY X-RAY ABSORPTIOMETRY

Total and regional bone mineral density (BMD) of the proximal femur wa s measured by DXA in 1238 healthy white women. In the 389 premenopausa l women, aged 21-54 years, no bone loss was observed before the menopa use, except in the femoral neck and Ward's triangle, in which BMD decr eased by 0.3%/year (SEE 0.2-0.9%/year, p < 0.001) and 0.6%/year (SEE 0 .4-0.8%/year, p < 0.001), respectively. In the postmenopausal women ag ed 48-75 years, there was a highly significant exponential decay in BM D with age and years since menopause (YSM) in all regions(-0.58 < r < -0.48, p < 0.001). However, YSM was a better predictor of BMD than age . The decrease in BMD in the first 5 years postmenopause reached value s of 9-13%. The estimated bone loss after 20 years was 17-30%, greates t in Ward's triangle and smallest in the intertrochanteric region, BMD correlated highly significantly with BMI (0.26 < r < 0.48, p < 0.001) . In conclusion, the present study indicates a stable premenopausal bo ne mass of the proximal femur and a postmenopausal bone loss, which is influenced mainly by YSM within the first 10-15 years after menopause . BMD correlated with body mass index (BMI) in the postmenopausal year s, confirming that low BMI constitutes a potential risk factor for ost eoporosis.