The Comparison Between Different Immunoassays for Serum Carbohydrate Antigen (CA 19-9) Concentration Measurement

INTRODUCTION: The carbohydrate antigen (CA 19-9) is a marker for pancreatic and colorectal carcinoma. In our study, we have investigated the level of CA 19-9 at 50 patients with benign and malign disease using three immunoassays. METHODS: The COBAS e 601 (Roche) uses an ECLIA, Architect i2000 analyzer (Abbott) uses CMIA and VITROS 5600 uses integrated System Intellicheck Technology with cut off 0.0-37.0 U/mL for determination of CA 19-9. Results were with a statistical significance of p < 0.05. RESULTS: Comparison of CA19-9 on COBAS with Architect show correlation coefficient R = 0.708. The results showed a regression line between immunoassay in patients with CA 19-9 treatment of y (Cobas) = 16.14 x (Architect) + 0.53. The comparison of CA19-9 on Architect and Cobas show correlation coefficient R = 0.709. The results showed regression line between immunoassay in patients with CA 19-9 treatment of y (Vitros) =–5.558 + 2.432 x (Architect) and correlation coefficient R = 0. 990. The mean concentration of CA 19-9 in the CMIA method was 41.49 U/mL, Intellicheck Technology was 103.45 U/mL and using ECLIA method was 47.25 U/mL at patients. CONCLUSIONS: Patients should be monitored on a single method to avoid differences in the results. The various immunoassay techniques for the detection of CA 19-9 tumor marker using different monoclonal antibodies, which leads to different results. Different antibodies recognize different parts of the molecule, and antigen heterogeneity may account in part for inter-method differences.