POSTMENOPAUSAL BONE LOSS OF THE PROXIMAL FEMUR - ESTIMATED CONTRIBUTIONS OF MENOPAUSE AND AGING

Femoral bone mineral density (BMD) was measured by dual energy x-ray a bsorptiometry (DEXA) in 680 normal postmenopausal women. Femoral neck, Ward's triangle, and trochanter densities were weakly correlated with height (correlation coefficient r = 0.11 to 0.22), but a stronger cor relation was found with body weight (r = 0.37 to 0.45) and body mass i ndex (BMI) (r = 0.36 to 0.43). Bone density showed a negative correlat ion with all ages in all femoral regions (r = -0.14 to -0.27), but the correlation with years since menopause (YSM) was higher (r = 0.23 to 0.35). When femoral bone densities were simultaneously regressed on BM I, age, and YSM, the correlation with YSM and BMI remained highly sign ificant, while the correlation with age was not significant, In 64 pai rs of postmenopausal women (one woman less than or equal to 60 years o f age and one >60 years of age; 56.8 +/- 2.6, and 64.8 +/- 2.9 years, respectively) matched for YSM (10.3 +/- 2.3 years), femoral bone densi ties were significantly (p < 0.001) lower in the younger (femoral neck , 0.783 +/- 0.90; Ward's triangle, 0.629 +/- 0.108; trochanter, 0.643 +/- 0.103 g/cm(2)) than in the older women (femoral neck, 0.826 +/- 0. 105; Ward's triangle, 0.681 +/- 0.138; trochanter, 0.689 +/- 0.108 g/c m(2)). In conclusion, beside the BMI, the menopausal component of bone loss and a younger age at the menopause represent the major factors i n predicting femoral bone density in women.