Bilateral femoral bone mineral density measurements in Chinese women and men.

The aim of this study was to assess the contralateral femoral bone mineral density (BMD) difference as measured by dual-energy X-ray absorptiometry (DXA) in mainland Chinese women and men. We measured bilateral proximal femora (i.e., total hip, femoral neck, upper femoral neck, and trochanter) using DXA in 1101 subjects (284 males, 817 females), among whom 504 were postmenopausal. Data were analyzed by descriptive statistics, Student's t-tests, and Pearson's correlation coefficients (r). With bilateral femur measurements and the acquisition of the mean BMD, precision error could be significantly reduced at the total hip, the femoral neck, and the upper femoral neck. Contralateral femoral BMD was highly correlated at all measuring sites (r=0.879-0.964). For the male group and for the postmenopausal subgroup, no significant differences in contralateral femoral BMDs were found. In the postmenopausal women, the percentage of subjects with discordance in classification (i.e., normal, osteopenia, and osteoporosis) for the left and right femora declined from 16.9% to 8.1% with precision adjustment. From a population perspective, since there may still be a considerable number of misdiagnosed cases, we therefore suggest that bilateral femur measurements may be justified for postmenopausal Chinese women.