[Evaluation of the latex turbidimetric immunoassay for CK-MB protein]

CK-MB protein is an important marker for the diagnosis of acute coronary syndromes. In the present study, we evaluated the basal performance of recently developed CK-MB mass kit "L-type wako CK-MB mass". Within-run and between-day precision were obtained with 1.4-4.7% and 2.7-5.2%, respectively. Diluted linearity and lower limit of detection were obtained with 180.0 ng/mL and 2.1 ng/mL, respectively. Zone phenomenon was able to detect until 25,600.0 ng/mL. Analysis of interferent showed that only CK-BB positively influenced the assay results. CK-MB protein levels decreased to 82% at 72 hours in the room temperature, but it was stable at 4 degrees C and -20 degrees C. The correlation coefficient(r) between this assay and conventional assay was 0.999. However, discrepancy of the two cases was observed in the comparison between the two methods. In the case 1, CK isoenzyme analysis using electrophoresis indicated that CK-MB was not present and absorption test showed a 68% absorption effect of CK-MB protein values not by anti human IgG, anti human IgA, and animal serums, but anti human IgM. In the case 2, CK isoenzyme analysis indicated that there is not only CK-MB but CK-BB. CK-MB protein values between the two methods were fitted after decreasing CK-BB. Thus, Value discrepancy for CK-MB protein was resulting from IgM and CK-BB. We have to pay attention to such phenomenon when detecting an unlikely higher levels that could not be explained by clinical information.