Growth in Bone Mass and Size—Are Racial and Gender Differences in Bone Mineral Density More Apparent than Real?

Abstract

In this issue of JCEM, Gilsanz and colleagues (1) (see page 1420) present data that give us insight into the racial differences in bone mass, bone size, and bone mineral density (BMD), which may partly contribute to the lower incidence of fractures in blacks than in whites. The work is refreshing reading because of the meticulous attention to study design and the resultant credibility of the observations.The investigators matched 80 black females and males with 80 whites of the same gender, age, bone age, pubertal stage, height, and weight, and report that: (i) blacks have higher volumetric apparent BMD of the cancellous (trabecular) bone of the vertebral body; (ii) there are no racial differences in femoral midshaft cortical thickness or its true BMD; (iii) blacks have longer legs and a larger femoral midshaft cross-sectional area, but shorter trunk length and vertebral height (despite having the same vertebral cross sectional area).