Ethnic differences in bone mass of young women vary with method of assessment.

To examine ethnic differences in bone mass measured by calcaneus ultrasound (CUS) and dual energy X-ray absorptiometry (DXA), and to compare the two methodologies, CUS was performed in 904 healthy Asian, African American, Latina, and Caucasian women 20-26 yr old using the Lunar Achilles Plus ultrasonometer. CUS measurements (broadband ultrasound attenuation [BUA] and speed of sound [SOS]) were made following standard methodology (standard CUS) and repeated adjusting for foot size using shims (with-shim CUS). Areal bone mineral density (BMD) and estimated volumetric bone density (BMAD) at the spine, femoral neck, and whole body were determined using the Lunar DPX-IQ. African Americans had greater height- and weight-adjusted BUA than Caucasians, while Asians and African Americans had greater SOS than Caucasians and Latinas. Additionally, African Americans had greater height- and weight-adjusted BMD and BMAD than all other groups. CUS and DXA measurements correlated moderately (r = 0.2-0.5). With-shim CUS values were 0.9-7.8% lower than standard CUS values. In conclusion, African American women had greater DXA measurements than all others and greater CUS measurements than Caucasians. In contrast to DXA, CUS measurements in Asians and Latinas were not significantly lower than those in African Americans. Most notably, Asians had greater values for SOS than Caucasians and Latinas. Discrepancies in ethnic comparisons and modest correlations suggest that CUS and DXA methods may capture different bone qualities.