QDR 4500A DXA overestimates fat-free mass compared with criterion methods

Frances A. Tylavsky, Timothy Lohman, Barbara A. Blunt, Dale A. Schoeller, Thomas Fuerst, Jane A. Cauley, Michael C. Nevitt, Marjolein Visser, Tamara B. Harris

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


This study evaluated the accuracy with which the dual-energy X-ray absorptiometer (Hologic QDR 4500A) measured fat-free mass (FFM), fat mass (FM), and hydration of FFM. In a study of 58 men and women (ages 70-79 yr), the QDR 4500A was found to provide a systematically higher estimate of FFM and lower estimate of FM than a four-component model of body composition. A correction factor from this study was developed and applied to two other samples (n = 13 and 37). We found mean corrected levels of FFM and FM to be equivalent to that obtained by the four-component model or total body water. In addition, the hydration of the corrected FFM was closer to the established hydration level in adult samples and that obtained from the four-component model. These findings suggest that the current calibration of the fan-beam system of the Hologic QDR 4500A provides an overestimate of FFM and underestimate of FM compared with reference methods.

Original languageEnglish (US)
Pages (from-to)959-965
Number of pages7
JournalJournal of Applied Physiology
Issue number3
StatePublished - Mar 1 2003
Externally publishedYes


  • Body composition
  • Dual-energy X-ray absorptiometer
  • Four-component model of body composition
  • Hydration of fat-free mass
  • Total body water

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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