EVALUATION OF BODY-COMPOSITION BY DUAL-ENERGY X-RAY ABSORPTIOMETRY AND 2 DIFFERENT SOFTWARE PACKAGES

Dual energy x-ray absorptiometry (DXA) measures body composition, tiss ue distribution, bone mineral content (BMC), and bone mineral density (BMD). Differences are possible due to software versions. This investi gation examined body composition, tissue distribution, BMC, and BMD me asurements using a DXA (Lunar Corp., Madison, WI) with different softw are packages (versions 3.4 and 3.6R). Fifteen women, ages 20-40 yr, en rolled in a weight-loss study (body mass index = 28) and volunteered f or body composition assessment by densitometry. BMC, BMD, and tissue d istribution measurements were made using DXA. Results were analyzed on ce each with software versions 3.4 and 3.6R. BMC + total soft tissue, measured using DXA, was comparable to measured body weight (3.4 = 76.3 kg; 3.6R = 76.5 kg; weight = 76.5 kg). Lower BMC and BMD (5.5% and 1. 8%, P < 0.01) were observed with 3.6R. Arm tissue mass was lower (1,53 0 g; P < 0.01) and fat declined (1,069 g; P < 0.01) with 3.6R. Leg tis sue mass decreased 487 g (P < 0.01), but fat tissue increased (526 g, P < 0.01) with 3.6R. A larger fat mass (1,492 g) and lower lean mass ( 1,115 g) were observed with 3.6R compared with 3.4. Percent fat values by densitometry using DXA 3.4 and 3.6R were 38.1%, 39.9, and 41.9%, r espectively. These results demonstrated differences in total body comp osition, lean and fat tissue distribution, and bone measurements from DXA software versions.