Within-subject variability in body composition using dual-energy X-ray absorptiometry.

The reproducibility of dual-energy X-ray absorptiometry (DXA) measurements for total body composition and for segmental body composition was investigated in 22 healthy male subjects who underwent six consecutive measurements in 90 min. Body weight (mean +/- SD) and body height were 72.3 +/- 8.8 kg and 1.75 +/- 0.04 m respectively, and body mass index was 23.5 +/- 2.5 kg m(-2). Bone mineral content (BMC) was 3.30 +/- 0.36 kg, lean mass and fat mass as measured by DXA were 57.1 +/- 6.1 kg and 11.8 +/- 6.5 kg respectively. For BMC, the reproducibility, expressed as the coefficient of variation, was 12%, 1.5%, 2.5%, 4.1% and 3.1% for total body, legs, arms, trunk and abdominal respectively. For lean tissue and for fat tissue, these values were 1.5% and 50%; 1.8% and 2.1%, 8.3% and 11.7%, 26% and 10.0%, 3.9% and 10.7% respectively. It is concluded that the reproducibility for BMC is excellent, but that for lean tissue and for fat tissue the variability is relatively high, especially in body segments.