Bilirubin interference with determination of uric acid, cholesterol, and triglycerides in commercial peroxidase-coupled assays, and the effect of ferrocyanide.

We examined the effect of bilirubin on measurement of serum uric acid, cholesterol, and triglyceride in the BMD-8700, Hitachi 705, Multistat III, CentrifiChem, Cobas-Bio, Ektachem 400, aca II, and RA-1000 analyzers. In general, bilirubin interferes more in peroxidase-coupled assays than in either direct methods or those coupled to NAD(P)+. The degree of interference, which can be spectral or chemical, varies and depends on the chromogen and wavelength used. We present data to show the origin and extent of the interference by bilirubin in these systems and demonstrate how ferrocyanide can provide a satisfactory resolution in some cases.