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Updated: Aug 13, 2026

One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure
Published on: June 25, 2010
A noninvasive method for measuring urea kinetics with a single dose of [15N15N]urea in free-living humans
A A Jackson1, M S Danielsen, S Boyes
1Department of Human Nutrition, University of Southampton, U.K.
Abstract:
A noninvasive method is described in which the endogenous rate of urea production can be determined in normal, free-living adults. A single dose of [15N15N]urea was given orally, and the amount of label excreted as [15N15N]urea and [15N14N]urea in urine over the subsequent 48 h was measured. From the rates of excretion of labeled and unlabeled urea the rate of urea production was derived. Using this single-dose protocol the rate of urea production was 207 +/- 56 (mean +/- SD) mg N/(kg.d) in six normal adult men consuming 74 g protein/d. These results were not different when compared with rates of urea production obtained with a prime/intermittent protocol in an earlier study in the same individuals [199 +/- 20 mg N/(kg.d)]. We conclude that urea kinetics can be measured noninvasively with a single dose of [15N15N]urea and that this method may be suitable for use in free-living individuals to determine urea production rates for habitual dietary intakes.
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