Effects of haemolysis, lipaemia and bilirubinaemia in canine C-reactive protein and haptoglobin determination by time-resolved fluorometry: short communication.

C-reactive protein (CRP) and haptoglobin (Hp) are well-known acute phase proteins in the dog. Currently, a commercial ELISA and a colorimetric assay are the methods of choice for measuring CRP and Hp, respectively; however, these assays showed interference when using haemolysed, lipaemic or hyperbilirubinaemic samples. Recently, time-resolved immunofluorometric assays (TR-IFMAs) have been developed for measuring canine CRP and Hp. The aim of the present study was to evaluate the effect of increasing concentrations of haemoglobin, lipids and bilirubin in CRP and Hp serum measurements using these new fluoroimmunoassays. Haemolysis was produced by freezing blood cells at -20 degrees C. The haemolysate was added to pooled sera at final concentrations of 0, 2.5, 5, 10, 20 and 40 g/L. A commercial emulsion of triglycerides was added to homologous pooled sera at 0, 0.35, 0.7, 1.4, 2.8, 5.6 and 11.2 mmol/L. Bilirubin, initially dissolved in dimethyl sulphoxide, was added to pooled sera at 0, 64.2, 128.4, 256.8, 513.7 and 1027.4 micromol/L. Addition of fresh haemolysate, triglycerides or bilirubin to serum samples did not affect either CRP or Hp concentrations (P > or = 0.18), so the TR-IFMAs could be an alternative to the traditional tests for measuring canine CRP and Hp in those laboratories where immunofluorometric assays are available.