title: Precision of DLW energy expenditure measurements: contribution of natural abundance variations.
abstract: Accuracy and precision of the the doubly labeled water (DLW) measurements of energy expenditure are commonly estimated with models that do not account for 2H and 18O natural abundance variation. A new and simple treatment that completes the ratio-product model is derived in the present study. It uses both linear regression of multipoint data with time and information on within-subject 2H and 18O natural abundance variation. Use of this treatment is demonstrated in a group of seven subjects in whom 2H and 18O natural abundance variation was assessed by collecting predose samples for 6-8 days before dosing. In this set of 16 measurements, the precision (coefficient of variation) of individual DLW estimates of CO2 production was 4.90 +/- 2.14%, of which 3.23 +/- 1.20% arose from natural abundance variation.
authors.affiliation: Dunn Nutrition Centre, Medical Research Council, Cambridge, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Ritz
authors.forename: T J
authors.initials: TJ
authors.lastname: Cole
authors.forename: C
authors.initials: C
authors.lastname: Couet
authors.forename: W A
authors.initials: WA
authors.lastname: Coward
mesh_terms: D000328:Adult; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D006859:Hydrogen; D007554:Isotopes; D008297:Male; D008954:Models, Biological; D010103:Oxygen Isotopes; D014867:Water / Q000378:metabolism*
chemical_list: D007554:Isotopes; D010103:Oxygen Isotopes; D014867:Water; D006859:Hydrogen