Precision of dlw energy expenditure measurements : contribution of
natural abundance variations.
Ritz, P., T. J. Cole, C. Couet, and W. A. Coward.
Dunn Nutrition Centre, Medical Research Council, Downhams Lane,
Milton Rd, CB4 1XJ Cambridge, United Kingdom, Present address :
Laboratoire de Nutrition Humaine, Centre de Recherche en Nutrition
Humaine, BP 321, 63009 Clermont-Ferrand, Cedex 1, France, Laboratoire
de Nutrition, Universit[acute]e F. Rabelais, 37000 Tours, France,
APStracts 2:0145E, 1995.
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 7 subjects where 2H and 18O natural
abundance variation was assessed by collecting pre-dose samples for
6-8 days before dosing. In this set of 16 measurements the precision
(CV) of individual DLW estimates of CO2 production was 4.90 +/-
2.14%, out of which 3.23 +/- 1.20% arose from natural abundance
variation.
Received 19 December 1994; accepted in final form 28 June 1995.
APS Manuscript Number E523-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.