Comparison of a new enzymatic assay for serum homocysteine on Toshiba TBA-c16000 against an immunoassay on Abbott Architect.

Homocysteine, a risk factor for cardiovascular disease, is commonly analyzed using enzymatic measurements and immunoassays. We compared the results of a new enzymatic assay with those of an immunoassay, using new reagents for homocysteine. The 87 serum samples were analyzed using the Abbott Architect i2000sr (immunoassay) and Toshiba TBA-c16000 (enzymatic assay), and the results obtained from the two assays were compared for precision, correlation, linearity, sample carryover, and reference range verification according to the Clinical and Laboratory Standards Institute guidelines. Repeatability and total imprecision were within the desirable range (Westgard QC, 4.15%). Correlation analysis revealed a strong correlation with a slope ranging from 0.9887 to 1.052, a correlation coefficient ( ) of 0.9886 [95% confidence interval (CI) of 0.9899-0.9968], and a y-intercept from -0.5741 to 0.6252. Linearity was acceptable ( = 0.9993), and the recovery rate was within ±10% of the expected value. The enzymatic assay showed an acceptable carryover rate (-0.15%) and a shorter turnaround time (10-12 min) compared with that of the immunoassay (30 min). Our new enzymatic assay for the measurement of homocysteine showed an acceptable performance in terms of precision, correlation, linearity, carryover test, cost-effectiveness, and speed.