BONE MASS AND HIP AXIS LENGTH IN HEALTHY ASIAN, BLACK, HISPANIC, AND WHITE AMERICAN YOUTHS

The primary objective of this study was to examine the associations of ethnicity, diet (calcium, protein, energy), and weight-bearing activi ty with dual-energy X-ray absorptiometry (DXA)-measured bone mass and hip axis length (HAL) in 423 Asians, blacks, Hispanics, and non-Hispan ic Caucasians, aged 9-25 years, Bone mass was expressed as bone minera l content (BMC), bone mineral density (BMD), and bone mineral apparent density (BMAD). The data were analyzed using multiple linear regressi on, after stratifying for gender and pubertal stage and adjusting for height and weight, With few exceptions, Asians and Hispanics had compa rable bone mass to whites at all pubertal stages, Greater femoral neck BMAD in black than white females was observed at all pubertal stages, Black males displayed greater BMD and BMAD than white males at all si tes in early puberty and at the femoral neck in maturity, Calcium was positively and protein negatively related to BMAD at the femoral neck in early pubertal females, Among males, calcium was negatively associa ted with whole body BMC and BMD and spine BMD and BMAD in midpuberty. Weight-bearing activity was not associated with bone mass in females; in males, it was positively related only to femoral neck BMC in early puberty. There was an absence of evidence for ethnic differences in HA L among females, In males, we observed shorter HAL in mature Asians an d blacks than whites,Neither diet nor activity was associated with HAL .