Minimal sampling protocol for accurate estimation of urea production: a study with oral [13C]urea in fed and fasted piglets

Oosterveld, Michiel J.S., Gemke, Reinoud J.B.J., Dainty, Jack R., Kulik, Willem, Jakobs, Cornelis and de Meer, Kees (2005) Minimal sampling protocol for accurate estimation of urea production: a study with oral [13C]urea in fed and fasted piglets. Clinical Nutrition, 24 (1). pp. 97-104. ISSN 0261-5614

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Background & aims: An oral [13C]urea protocol may provide a simple method for measurement of urea production. The validity of single pool calculations in relation to a reduced sampling protocol was assessed. Methods: In eight fed and five fasted piglets, plasma urea enrichments from a 10 h sampling protocol were measured following an intragastric [13C]urea bolus. Blood [13C]bicarbonate was measured to trace gut [13C]urea oxidation. Two-compartment and regression (single pool) computations were performed. Pool sizes were compared to urea distribution over total body water (TBW). Shorter protocol duration was tested in regression simulations. Results: Differences in urea kinetics between fed and fasted piglets did not reach statistical significance. Mean (±SE) urea pool from TBW times plasma urea concentration was 2.2±0.16 mmol kg−1. Two-compartment modelling yielded similar results for pool size (despite the oxidation of a small amount of urea tracer). Urea appearance rate was 306±18 μmol kg−1 h−1. Regression calculations overestimated urea appearance rate vs. compartmental model (). When samples <2 h were discarded, results were comparable to compartmental calculations even if protocol length was 6 h (325±24 μmol kg−1 h−1, NS). Conclusions: Regression calculations using plasma enrichments sampled between 2 and 6 h after oral [13C]urea administration provide accurate rates of urea production, and are not affected by tracer oxidation.

Item Type: Article
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: Pure Connector
Date Deposited: 27 Feb 2018 15:30
Last Modified: 04 Oct 2020 23:53
DOI: 10.1016/j.clnu.2004.07.017

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