DEMONSTRATION THAT BONE-MINERAL DENSITY OF THE LUMBAR SPINE, TROCHANTER, AND FEMORAL-NECK IS HIGHER IN BLACK THAN IN WHITE YOUNG MEN

The incidence of osteoporosis and fractures of the hip and spine is lower in black than in white subjects. To determine whether bone mass is increased in black men and to assess the influence of body weight and age, bone mineral density (BMD) of the lumbar spine, trochanter, and femoral neck was measured by dual-photon absorptiometry in 59 normal white men and 40 black men between the ages of 20 and 50 years. Body weight and age were not different from each other in the two groups. BMD of the midradius was measured by single-photon absorptiometry. Multivariate regression was used for independent analysis of each group and for analysis of the two groups together. After adjusting for body weight, age was inversely related to BMD of the femoral neck in both blacks and whites and of the trochanter in blacks. When body weight was analyzed independently of age, it was a positive predictor for BMD of the midradius of black men and of the femoral neck in white men. Despite the racial differences in age and weight on BMD, there were no significant interactions between race and age or race and weight when the data from black and white men were combined. Race had a highly significant effect on BMD of the lumbar spine, trochanter, and femoral neck midradius, and BMD was higher in blacks than in whites at these sites. There were significant declines in BMD with age at the midradius and femoral neck and significant increases in BMD with body weight at the trochanter and femoral neck. Thus, bone mass is higher in black than in white men and the difference in bone mass may contribute to the lower incidence of osteoporosis and fractures in blacks.