Modification of Jaffe's Kinetic Method for Serum Creatinine Estimation to Decrease Bilirubin Interference

Abstract

Background and Objectives: Bilirubin causes negative interference in creatinine value measurement using general techniques.The objective of this study was to find a method of serum creatinine estimation in which interference of bilirubin is minimized. Method: The study was conducted in the Clinical Chemistry Laboratory SSG Hospital, Vadodara. 60 samples with different levels of serum bilirubin were grouped as group I (1-5mg/dl), group II (5-15mg/dl), group III (>15mg/dl). Both creatinine and bilirubin concentration in serum samples were measured by using semiautoanalyzer in laboratory. The creatinine value was measured by two variations of Jaffe’s kinetic Method A (preincubation with NaOH) & Method B (without preincubation) and Total bilirubin measured by Diazo method using commercial kits. Results: The mean value of creatinine was different for preincubation with NaOH and without preincubation. Results of the Method-A (with NaOH Preincubation) & B (without NaOH Preincubation) were compared in all the 3 groups and are as follows. The mean difference was higher at higher bilirubin level & difference was statistically significant at bilirubin >5mg/dl. Conclusion: This shows that the bilirubin has negative interference in creatinine value measurement by ordinary laboratory practices and interference increases with higher concentration of bilirubin in blood sample. We conclude that preincubation with NaOH helps to reduce this negative interference of bilirubin in creatinine value measured by Jaffe Method in icteric serum sample. [Sumitra C NJIRM 2017; 8(2):130-132]