Body composition measurements by dual-energy x-ray absorptiometry differ between two analysis modes.

This study was undertaken to determine to what extent body-composition measurements by dual-energy X-ray absorptiometry (DXA) differed between two analysis modes (standard vs extended). Whole-body bone mineral density (BMD), bone mineral content (BMC), bone area (BA), fat mass (FM), lean mass (LM), and percentage of fat (%fat) of 263 women, aged 20-74 yr, were measured by DXA, with each scan analyzed by both the standard and extended analysis modes. The standard mode had significantly higher values for BMD, BMC, BA, and %fat, and significantly lower values for LM than extended mode (p < 0.05). The measurement error of BMC was highly correlated with the measurement error of BA (r = 0.93), thereby indicating the possibility of bone-edge instability by different analysis modes. Body mass index (BMI) was also significantly correlated with the measurement error of BMC (r = 0.75). The degree of obesity might be tightly associated with the occurrence of the measurement error. Caution is recommended when different analysis modes are used for making multicenter comparisons or assessing intervention-induced changes.