Determination of creatinine in human serum and urine by reversed-phase high pressure liquid chromatography

Objective To evaluate the analytical variables of the reversed-phase high pressure liquid chromatography (HPLC) with 5-Fluorouracil(5-Fu) as an internal standard for determining creatinine in human serum and urine. The method was used as a candidate reference method for accuracy assessment of routine creatinine test kits.Methods We tested the accuracy, precision, linearity of the reversed-phase HPLC.We analyzed split samples of a panel of 85 patients’ serum and 94 patients’ urine and compared the results of the routine test kits and HPLC by means of bias plots (percentage differences of results) and standard linear regression.Results The linear range of HPLC method was up to 2 210 μmol/L, the within-run CV(n=5) was below 2.5% and the between-day CV(n=10) was less than 4.5%. The analytical recovery rate was 96.3%～102.4%. All of the test kits correlated very well with HPLC.Conclusions We recommend the reversed-phase HPLC with 5-Fu as an internal standard as a candidate reference method for determining creatinine in human serum and urine.The enzymatic method with creatininase coupled sarcosine oxidase is suitable for routine work in clinical laboratories.