Serum creatinine and the DuPont dimension: possible improvements.

A study is reported on the determination of creatinine with the DuPont Dimension, paying special attention to interference by bilirubin. Various methods for dealing with bilirubin interference are described, including modification of the Jaffé reaction, enzymatic assay of creatinine, enzymatic destruction of bilirubin, and ultrafiltration of the serum sample. None of these modifications gave completely satisfactory results, although the Jaffé method with a ferricyanide oxidation step, and the enzymatic assay with ferrocyanide gave reasonable results with icteric specimens from adult patients, while only the latter method could be used for neonatal serum samples.