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

Measurement 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.The criteria of analytical performance for each assay and the correlation between methods were evaluated.Both assays were linear over the range 0 to 500 micromol/L of pyruvate. The total precision of the HPLC and enzymatic method were <5% for pyruvate concentrations ranging from 28 and 213 micromol/L and 42 and 181 micromol/L, respectively. The limit of detection for the HPLC technique was determined to be 1 micromol/L and the limit of quantification was 5 micromol/L. The mean recovery for HPLC was 99%. Results for the enzymatic assay showed a limit of detection of 5 micromol/L and a limit of quantification of 10 micromol/L. The mean recovery was 90.4%. In the method comparison, the HPLC method gave values that were on average 24 micromol/L higher than the enzymatic assay.Both 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.