Four commercial urease reagents and a laboratory-prepared reagent compared for analysis of blood urea nitrogen with the Beckman analyzer.

Three laboratory-prepared urease reagents were compared with a commercial preparation supplied for routine use on the Beckman Blood Urea Nitrogen Analyzer. There were discrepancies in results for urea nitrogen among the four urease reagents when matching serum and the corresponding oxalate/fluoride treated plasma were compared as measured with the Beckman Analyzer and continuous-flow (AutoAnalyzer) method. All four urease preparations were affected by fluoride, but to different extents. We believe that an effective laboratory reagent can be prepared in the laboratory at significantly lower cost.