Interference of Bilirubin in Serum Creatinine Estimation by Jaffe Reaction and Creatinase Method

Abstract

Serum creatinine determination is crucialin assessing renal functions. Jaffe reaction is used world-wide in serum creatinine estimation. It has been reported that bilirubin affects Jaffe reaction causing underestimation. However, Creatinase method has little interference but is comparatively more expensive. The objective of this study was to compare the creatinine concentrations of serum with different bilirubin levels using Jaffe reaction and Creatinase method. Three serum pools were placed in an infant phototherapy incubator for 18 hours to photolysis the bilirubin. Serum creatinine concentration of each pool was measured by Creatinase method and the values were 0.51, 2.41 and 7.33mg/dL. Each serum pool was then spiked with eleven different bilirubin concentrations.The bilirubin concentrations of the spiked serum were 0, 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30mg/dL. The total bilirubin, creatinine by Jaffe reaction and Creatinase method were measured by Indiko TM clinical and specialty chemistry system. Results were analyzed by linear regression analysis. According to the Creatinase method, there was no significant underestimation in serum with 0.51mg/dL of creatinine but Jaffe reaction showed a significant underestimationfrom bilirubin concentration of 7.18mg/dL. In serum with 2.41mg/dL of creatinine, Creatinase method and Jaffe reaction were given significant underestimations by bilirubin concentrations of 9.05 and 5.64mg/dL, respectively. In serum of 7.33mg/dL creatinine, significant underestimations were given from bilirubin levels of 3.6 and 8.18mg/dL by Creatinase method and Jaffe reaction, respectively. According to the present study, Creatinase method is reliable in estimation of serum creatinine of ≤0.51mg/dL.