ETHNIC-DIFFERENCES IN REGIONAL BONE-DENSITY, HIP AXIS LENGTH, AND LIFE-STYLE VARIABLES AMONG HEALTHY BLACK-AND-WHITE MEN

There are few published data on bone mass, measured by dual-energy X-r ay absorptiometry (DXA), in healthy white or black men. Similarly, a r ecently described predictor of hip fracture among white women, hip axi s length (HAL), has not been studied in men. We recruited 160 white an d 34 black men, aged 23-80 years, and screened for diseases and drug e xposures that adversely affect skeletal health. We measured bone miner al density (BMD) in the lumbar spine, femoral neck, and radial shaft b y DXA height and weight; skin color by reflectometry; and hip aids len gth both directly from DXA output and using automated software in a su bsample. We also obtained historical data on education, smoking, exerc ise, and fractures. There were no significant black/white differences in mean weight, height, body mass index (BMI), or HAL. The black men h ad higher BMDs than did the white men at every site (5% for the radius , 10% for the lumbar spine, and 20% for the femoral neck). Skin pigmen tation and BMD were not significantly correlated in either group (p > 0.38). Among the white men, smoking was associated with lower lumbar B MD, but there was no significant relationship between BMD and exercise frequency in either group. There was no significant ethnic difference in fracture experience. We conclude that: (1) the higher BMD in black men than in white men is not due to greater body size, (2) the lower hip fracture risk reported for black men than for white men is not due to a difference in hip axis length; (3) skin color is not related to BMD in either sex.