A simple enzymatic method for the measurement of abnormal levels of formate in plasma

A simple and practical method designed to measure abnormal concentrations of plasma formate is described. The method uses formate dehydrogenase and a color reagent to produce a stable formazan color. The method requires no deproteinization and has a one-point standard calibration. The precision at 1.0 and 5.0 mmol/L formate is 2.9% and 1.7% within-day and 5.5% and 2.3% between-day. Recovery averages 100% for formate concentrations of 2.0 to 10.0 mmol/L. The proposed method is inexpensive, robust, and suitable for routine use and shares the color reagent used for the assay of plasma lactate and 3-hydroxybutyrate, both important analytes in metabolic acidosis.