Elimination of bilirubin interference in creatinine assays by routine techniques: comparisons with a high performance liquid chromatography method.

The aim of this study was to find a method for creatinine analysis unaffected by jaundice by comparing four different methods with high performance liquid chromatography (HPLC) as a reference method. The methods investigated were Kodak DTSC single slide, Boehringer alkaline picrate with and without blank correction and a Boehringer enzymatic method, the last three using the Hitachi 737 analyser. HPLC results were compared with the results of the methods studied. In addition, graphs plotting the difference from the HPLC result against the bilirubin concentration were made; the ideal method would yield a slope and intercept of zero. While all methods showed a positive bias compared with HPLC, the Kodak slide and the Boehringer alkaline picrate with blank correction methods eliminated bilirubin interference and we have changed to the latter method as a consequence of this work.