Bilirubin interference on a Roche creatinine enzymatic method.

This letter addresses the impact of icterus interference (IF) on serum creatinine measurement using Roche enzymatic methodology, focusing on bilirubin's effect on assay accuracy. The authors conducted experiments using pooled pediatric and adult sera containing both conjugated and unconjugated bilirubin, finding that significant negative interference on creatinine results occurs when total bilirubin exceeds 400 µmol/L (24 mg/dL), with potential underestimation up to 20% at 650 µmol/L (39 mg/dL). Contrary to claims in the Roche kit insert, their data showed no evidence that conjugated bilirubin causes interference at lower concentrations than unconjugated bilirubin. Their clinical practice involves reporting creatinine results with bilirubin levels up to 400 µmol/L and, in urgent cases, up to 650 µmol/L with cautionary comments to clinicians to mitigate risks in patient management. [Extracted from the article]