Bilirubin Interference in Serum Creatinine Estimation by Jaffe's kinetic Method and Its Rectification in Three Different Kits.

The negative interference by bilirubin in serum creatinine estimation by Jaffe's kinetic method is well known. Several approaches have been suggested to overcome this interference. In this article three different creatinine kits (Jaffe's kinetic method) have been tested for bilirubin interference and its rectification using two simple approaches. The performance of three kits (A, B and C) supplied by three different manufacturers was tested using IQC and EQAS sera and pooled serum with added bilirubin. To overcome the bilirubin interference two approaches viz. NaOH preincubation and TCA precipitation were used. Bilirubin did interfere in creatinine estimation after a certain level (2.3 mg/dl). However, both NaOH preincubation and TCA precipitation approach rectified this interference. The performance of kit A was better than kit B and C. All the three kits showed bilirubin interference upon increasing the bilirubin concentration but kit A performed better than kit B and C. However, NaOH incubation and TCA precipitation methods overcame this interference to a great extent.