title: Dilution space ratio of 2H and 18O of doubly labeled water method in humans.
abstract: Variation of the dilution space ratio (Nd/No) between deuterium ((2)H) and oxygen-18 ((18)O) impacts the calculation of total energy expenditure (TEE) by doubly labeled water (DLW). Our aim was to examine the physiological and methodological sources of variation of Nd/No in humans. We analyzed data from 2,297 humans (0.25-89 yr old). This included the variables Nd/No, total body water, TEE, body mass index (BMI), and percent body fat (%fat). To differentiate between physiologic and methodologic sources of variation, the urine samples from 54 subjects were divided and blinded and analyzed separately, and repeated DLW dosing was performed in an additional 55 participants after 6 mo. Sex, BMI, and %fat did not significantly affect Nd/No, for which the interindividual SD was 0.017. The measurement error from the duplicate urine sample sets was 0.010, and intraindividual SD of Nd/No in repeats experiments was 0.013. An additional SD of 0.008 was contributed by calibration of the DLW dose water. The variation of measured Nd/No in humans was distributed within a small range and measurement error accounted for 68% of this variation. There was no evidence that Nd/No differed with respect to sex, BMI, and age between 1 and 80 yr, and thus use of a constant value is suggested to minimize the effect of stable isotope analysis error on calculation of TEE in the DLW studies in humans. Based on a review of 103 publications, the average dilution space ratio is 1.036 for individuals between 1 and 80 yr of age.
authors.affiliation: Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin; Japan Society for the Promotion of Science, Tokyo, Japan; Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan; and.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sagayama
authors.affiliation: Department of Nutritional Science, National Institutes of Biomedical Innovation, Health and Nutrition, Health and Nutrition, Tokyo, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin;
authors.forename: Natalie M
authors.initials: NM
authors.lastname: Racine
authors.affiliation: Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin;
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Shriver
authors.affiliation: Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin; dschoell@nutrisci.wisc.edu.
authors.forename: Dale A
authors.initials: DA
authors.lastname: Schoeller
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001834:Body Water / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003903:Deuterium / Q000652:urine*; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D007223:Infant; D008297:Male; D008875:Middle Aged; D010103:Oxygen Isotopes / Q000652:urine*; D014867:Water / Q000378:metabolism*; D055815:Young Adult
chemical_list: D010103:Oxygen Isotopes; C000615259:Oxygen-18; D014867:Water; D003903:Deuterium
keywords: dilution space; doubly labeled water; stable isotope; total energy expenditure