Methodological issues in comparing genetic and environmental influences on bone mass.

Measurements of bone mineral content (BMC), bone width (BW) and BMC/BW (BMA) at the proximal radius were compared for both Japanese and Japanese-American men and women, after adjusting for measurement technique differences. Within each nationality, men had greater values than women at all ages. Japanese-Americans had substantially greater values of BMC (6-10%) and BMA (16-17%), but lower BW (-12 to -15%), relative to Japanese. Adjustment for body size (height and weight) reduced the magnitude of these differences by approximately one-half for BMC, but had a smaller effect on BMA, and slightly increased the difference in BW. Comparison of these results to published data suggests that environmental factors may have influences on bone mass that are similar in magnitude to the effects of race. The need for additional studies to address potential methodological problems is discussed, using this and other reports as examples.