Metodjämförelse mellan instrumenten Vitros 5,1 FS och QuikRead CRP för analysen P-CRP

Sammanfattning: In studies of serum, in the early 1930s, from patients with pneumonia, a factor was found. It could agglutinate certain pneumococcal species. This factor, which later became known as C-reactive protein (CRP), increased sharply during the early and middle stages of the disease. CRP was identified as an acute phase protein and found especially in bacterial infections. CRP is synthesized in the liver by stimulation of interleukin 6 (IL-6), which is produced by the monocytes, and consists of five non-covalently bound subunits. The aim of this study was to compare two different analytical instruments (Vitros 5.1 FS Ortho-Clinical Diagnostics and QuikRead CRP Orion Diagnostica) for CRP analysis. In this study, Vitros 5.1 FS is used as a reference instrument. QuikRead CRP is a small instrument intended for patient-near testing. Vitros 5.1 FS (Ortho-Clinical Diagnostics a Johmon-Johmon Company, Rochester, NY, U.S.A) is a fully automated instrument for measuring various analytes of clinical importance in body fluids. For analysis of CRP, plasma is used. The amount of CRP is obtained by measuring turbidity at a specific wavelength in an Immuno-turbidimetric reaction. QuikRead CRP (Orion Diagnostica, Espoo, Finland) is an immuno-turbidimetric test in which micro-particles coated with anti-human CRP are used to measure the amount of CRP in whole blood, plasma or serum. Comparison between Vitros 5.1 FS and QuikRead CRP for the P-CRP analysis shows a good correlation (R= 0.997) of the mean value from the analysis I, II and III.  An intercept of -8.52 shows a decrease in the values of CRP for QuikRead comparatively Vitros 5.1 FS.  Bland-Altman-plot shows a slightly increased spread of results. Paired T-test shows that Vitros 5.1 FS and QuikRead CRP does not produces the same results. This study shows that QuikRead CRP is a user-friendly instrument that fits well in near patient testing. QuikRead CRP and Vitros 5.1 FS did not give the same results of P-CRP. This does not affect the results in regards to distinguish a viral infection (10-50 mg / L) from a bacterial infection (> 100 mg / L).