NHANES 1999-2004 DXA (FitnessNorms derivation)
About this reference
FitnessNorms derived these percentiles from the public NHANES 1999-2000, 2001-2002 and 2003-2004 whole-body DXA, demographic and body-measure files: 13,091 adults aged 20 and over with DXA data. Six-year examination weights were built per NCHS guidance, every percentile was computed within each of the five NHANES imputations of the DXA data and averaged, and lean mass is lean soft tissue excluding bone mineral. Before any value was published, the same pipeline reproduced the National Center for Health Statistics' own published percentiles for these years (Vital Health Stat 11(250)): all 104 sample sizes exactly and all 936 percentiles within two units of the last printed digit. Kelly et al. 2009 is kept as an informational comparison.
Known limitations
- Measured on Hologic QDR-4500A scanners with the Schoeller calibration; results from other DXA brands or calibrations are not directly comparable.
- DXA was not performed in pregnancy, and those participants are excluded. NCHS imputed DXA values for other participants who were not scanned (over the scanner's weight or height limits, or for other reasons) and for invalid regions; the percentiles use those imputations.
- Describes the US civilian noninstitutionalised population in 1999-2004.
- Cross-sectional: each age bracket is a different group of people, not individuals followed over time.
- Our values run slightly above NCHS's printed values for the same years (on average about 0.06 units in the kilogram tables and 0.10 in the percent-fat tables), within the pre-registered tolerance; the difference is not explained.