Comparison of high-performance liquid chromatography with fluorescence detection versus enzymatic assay to measure blood pyruvate in clinical practice

ObjectivesMeasurement of blood pyruvate allows the diagnosis of patients with mitochondrial disorders. The aim of this study was to assess the analytical performance of an HPLC and an enzymatic assay for quantifying pyruvate.MethodsThe criteria of analytical performance for each assay and the correlation between methods were evaluated.ResultsBoth assays were linear over the range 0 to 500 μmol/L of pyruvate. The total precision of the HPLC and enzymatic method were < 5% for pyruvate concentrations ranging from 28 and 213 μmol/L and 42 and 181 μmol/L, respectively. The limit of detection for the HPLC technique was determined to be 1 μmol/L and the limit of quantification was 5 μmol/L. The mean recovery for HPLC was 99%. Results for the enzymatic assay showed a limit of detection of 5 μmol/L and a limit of quantification of 10 μmol/L. The mean recovery was 90.4%. In the method comparison, the HPLC method gave values that were on average 24 μmol/L higher than the enzymatic assay.ConclusionBoth techniques demonstrated good analytical performance. The negative bias observed for the enzymatic assay can be explained by its lesser good recovery compared to the HPLC assay.