THE EFFECT OF ETHNICITY ON APPENDICULAR BONE MASS IN WHITE, COLORED AND INDIAN SCHOOLCHILDREN

Ethnic differences in the incidence and prevalence of osteoporosis hav e been shown throughout the world. In South Africa the prevalence of o steoporosis is much higher in whites than in blacks. This is surprisin g, since factors that might predispose to reduce bone mass are more pr eponderant in black communities. The present research was undertaken t o determine whether differences in bone mass during the period of bone accretion could explain the difference in the incidence of osteoporos is. In this paper we report on differences in appendicular bone mass b etween white, coloured and Indian children and teenagers (6 - 18 years ) from Johannesburg. The effects of weight, height, puberty and skinfo ld thickness on bone mass were also assessed. The bone width (BW) of w hite boys was greater than that of Indian boys, while the bone mineral content (BMC) and BMC/BW were greater in white boys than in both Indi an and coloured boys. After adjustment for differences in weight and h eight, the BW of coloured boys was significantly greater than that of white boys, while all differences in BMC and BMC/BW became non-signifi cant. For girls there were no significant differences in bone mass mea surements, but after adjustment for height and weight coloured girls h ad significantly greater BMC and BMC/BW than either white or Indian gi rls. This greater weight- and height-adjusted bone mass in coloured gi rls is consistent with the impression of a lower incidence of osteopor osis in coloured women than in white women.