title: Doubly labelled water: Multi-point and two-point methods in pre-school children.
abstract: OBJECTIVE
  We compared the multi-sample and two-sample methods for measuring total energy expenditure (TEE) using doubly labelled water (DLW) in pre-school children to establish whether taking multiple samples provides any advantage in free-living conditions.
  
  
  METHODS
  Sixty-five children (32 boys; aged 2-6 years) were recruited from Aberdeen, UK. TEE was measured over 7 and 14 days using the multi-point and two-point methods by DLW. Total body composition was measured using dual-energy X-ray absorptiometry.
  
  
  RESULTS
  There was no significant difference between the mean TEE estimated using the multi-point and two-point methods. Independent of sampling technique, there was no significant difference in the TEE estimated over 7 and 14 days. Correlation of the deviations of the day-to-day enrichments suggests that the major factors driving isotope affected both isotopes. Association between fat-free mass (FFM) and TEE over 14 days was higher when using the multi-point method (r(2)=57.7%, P<0.001) compared with the two-point method (r(2)=41.1%, P < 0.001). There was no systematic bias in the difference between the two methods.
  
  
  CONCLUSIONS
  Multi- and two-point approaches give similar results for calculation of daily TEE in pre-school children. For studies aiming to establish a population level of TEE the two-sample method is a cost effective approach. However, the multi-point method appears to have greater accuracy and precision based on the better relationship to FFM (or FFM and FM combined). Consequently where maximum precision is required, in particular when energy expenditure of individual subjects is needed, this approach may be more appropriate.
authors.affiliation: Aberdeen Centre for Energy Regulation and Obesity, Rowett Research Institute, Bucksburn, Aberdeen, United Kingdom.
authors.forename: Kurosh
authors.initials: K
authors.lastname: Djafarian
authors.forename: Diane M
authors.initials: DM
authors.lastname: Jackson
authors.forename: Eric
authors.initials: E
authors.lastname: Milne
authors.forename: Paula
authors.initials: P
authors.lastname: Roger
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
mesh_terms: D015502:Absorptiometry, Photon; D001823:Body Composition; D002245:Carbon Dioxide / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D017666:Deuterium Oxide; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011865:Radioisotope Dilution Technique; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D017666:Deuterium Oxide