Comparison of three commercial assays for the determination of serum C-reactive protein

Abstract EN

C-reactive protein (CRP) is one of the acute phase reactants pro¬duced by hepatocytes following trauma.

Serial measurement of serum CRP is reported to be valuable in monitoring patients admitted to the intensive care unit (ICU).

This report compared the use erf three commercial assays for the routine determination of serum CRP.

Two of the assays were quantitative (Tina-Quant (TQ) and Abbott TDx) whereas the other assay was semi- quantitative (Mercia latex agglutination).

The effect of lipaemia on the meas¬urement of CRP by immunoturbidimetry was also examined.

Serial serum samples (n = 97) from IS patients admitted to the ICU with multiple fractures (n = 7), myocardial infarction (n—4), hepatorenal failure (n-1), haematemesis (n = 2), and pancreatitis (n = l) were analyzed for CRP concentrations.

Good correlation (r2 = 0.96) was obtained between the TQ and TDx assays in contrast to that obtained with Mercia (r2=0.56 and 0.54, respectively).

TQ assay gave significantly (P < 0.005) lower CRP results than that of TDx.

Lipaemia resulted in ambiguous CRP results by immunoturbidimetry, the effect being due to op¬tical interference rather than to lipid micelles binding to CRP molecules.

In conclusion, the Mercia method was labor-intensive and time-consuming, whereas the TQ and TDx assays were fast and easy to perform ; however, in contrast to Mercia, required dedicated expensive equipment.

Interference by lipaemia was eliminated by serially diluting the sample or by ultra-centrifugation.

Determination of CRP in serial samples from intensive care pa¬tients was useful in early detection of sepsis.