The objective of this study was to compare the measurement of areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) with the measurement of volumetric bone mineral density (vBMD) by high-resolution peripheral computerized tomography (HR-pQCT) in subjects with a wide range of body mass indices (BMI).SUBJECTS/METHODS:
We scanned the arms and legs of 49 premenopausal women, aged 21-45 years, with BMI from 18.5 to 46.5, by HR-pQCT and found that there was a nonsignificant change in vBMD associated with increased BMI, whereas aBMD (DXA) was associated with a positive significant increase. HR-pQCT scans a slice at the extremity of the tibia and radius, whereas DXA scans the entire leg and arm.RESULTS:
The correlation coefficients (r) of BMD (DXA) of the legs with BMI were 0.552, P < 0.001, with %fat it was 0.378, P < 0.01 and with W it was 0.633, P < 0.001. The r of BMD (DXA) of the arms with BMI was 0.804, P < 0.001, with %fat it was 0.599, P < 0.001 and with W it was 0.831, P < 0.001, whereas the r of the average bone density (D100) of legs and arms measured by HR-pQCT with BMI, W and %fat were not significant.CONCLUSIONS:
Although HR-pQCT and DXA scan different parts of the bone, the high r of BMD with BMI and low r of bone density measured by HR-pQCT with BMI suggest that BMD measured by DXA is artifactually increased in the presence of obesity.