AJP - Endocrinology and Metabolism, Vol 270, Issue 1 E164-E169, Copyright © 1996 by American Physiological Society
Precision of DLW energy expenditure measurements: contribution of natural abundance variations
P. Ritz, T. J. Cole, C. Couet and W. A. Coward
Dunn Nutrition Centre, Medical Research Council, Cambridge, United Kingdom.
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.
