Background:
Traditional methods for measuring C-reactive protein (CRP) are precipitation and agglutination assays, however these methods have low sensitivity and provide only qualitative results. Recently highly specific antibodies have permitted the
development of rapid, specific, and very sensitive assays for CRP. These newer immunoassays include nephelometry, turbidimetry, radioimmunoassay, and enzyme immunoassay and have created a renewed interest in CRP testing in a variety of clinical
settings. We compared two quantitative methods of CRP measurement between nephelometry and fluorescence polarization immunoassay (FPIA) to assist the selection of test method.
Methods:
We evaluated the results of CRP measured by both methods in the sera from 107 patients. One and three control materials were used in the within-run and between-run precision study of nephelometry and FPIA, respectively. And we analysed the
interfering effect by hypertriglyceridemia.
Results:
Within- and between-run CVs were 2.2% and 3.9% in nephelometry, 0.4-4.2% and 2.1-9.8% in EPIA, Linearity of the nephelometry using serial dilution of C-reactive protein control serum showed good result (r=0.999). The results of the two methods
were
closely correlated (r=0.975). We observed an interference effect caused by high serum concentration of triglyceride greater than 600 mg/dL when CRP was measured by nephelometry.
Conclusions:
We conclude that each laboratory has no problem in quantitation of CRP even if the user selects any of two methods for CRP measurement because nephelometry and FPIA revealed nearly equal diagnostic performance.
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