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July 1990

Lifelong Black-White Differences in Bone Size and Cortical Area

Author Affiliations

Center for Human Growth and Development University of Michigan 300 N Ingalls, 10th Level Ann Arbor, MI 48109

Am J Dis Child. 1990;144(7):750-751. doi:10.1001/archpedi.1990.02150310016012

Sir.—It is a distinct pleasure to discover that Li et al1 have been able to confirm our earlier findings on black-white differences in skeletal mass and volume even in the preschool years. Despite differences in technology (direct photon absorptiometry vs radio-grammetry), in anatomical site (forearm vs hand), and in the samples considered, we are in agreement that black children (like black adolescents and adults) have larger skeletal dimensions once birth differences are erased, and they have larger bone masses as well.2-4

Since our sample of 1163 white children and 675 black children is considerable, it is possible to show how the relative magnitude of the differences increases from the first through the sixth year. Arranging our single-year data to agree with the 2-year age groupings used by Li et al, black-white differences in total bone width increased from 1% to more than 7% (Table). Differences in cortical