QDR 4500A dual-energy X-ray absorptiometer underestimates fat mass in comparison with criterion methods in adults

• Published in: The American journal of clinical nutrition Vol. 81; no. 5; pp. 1018 - 1025
• Main Authors: Schoeller, D.A, Tylavsky, F.A, Baer, D.J, Chumlea, W.C, Earthman, C.P, Fuerst, T, Harris, T.B, Heymsfield, S.B, Horlick, M, Lohman, T.G
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01-05-2005; American Society for Clinical Nutrition, Inc
• Subjects: Absorptiometry, Photon - methods; Adipose Tissue; Adult; Adults; age; Aged; Biological and medical sciences; Body Composition; Body fat; body mass index; Body Water; Comparative analysis; dual-energy X-ray absorptiometry; estimation; fat free mass; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; lean body mass; Male; men; Middle Aged; National Health and Nutrition Examination Survey; Nutrition Surveys; reference standards; Reproducibility of Results; United States; Vertebrates: anatomy and physiology, studies on body, several organs or systems; women; X-rays; United States; Human; Water; Energy; Hydration; Criterion; Adult; X ray; total body water; Fat mass; Body composition; Comparative study
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/81.5.1018

Background: Dual-energy X-ray absorptiometry (DXA) has become one of the most frequently used methods for estimating human body composition. Although the DXA technique has been validated for the measurement of fat-free mass and fat mass, differences in calibration between instruments produced by different manufacturers, as well as between different models produced by the same manufacturer, have been reported. Objective: The objective was to compare the calibration of the QDR 4500A against criterion methods in a large heterogeneous population. Design: DXA-derived body-composition data were obtained from 7 studies: 6 data sets were provided by the investigators, one of which was published. The data included fat mass and fat-free mass measured with a QDR 4500A and criteria measurements of body composition from total body water by dilution at 4 centers, densitometry from 1 center, and four-compartment analysis at 2 centers. Results: In the cohort of 1195 subjects, 602 men and 593 women aged 19-82 y with a body mass index (in kg/m2) of 16-44, the fan-beam DXA overestimated fat-free mass (P < 0.05). A significant difference was observed in all 7 data sets, and the mean (+/-SE) was 5 +/- 1%. Conclusions: It is recommended that the lean soft tissue mass estimate with the fan-beam QDR 4500A be reduced by 5% and that for fat mass be increased by that same mass. This finding is particularly important because the National Health and Nutrition Examination Survey is using the QDR 4500A to assess body composition in a nationally representative sample of persons in the United States.