2020 Volume 69 Issue 4 Pages 646-651
Recently, there have been reports of falsely high levels of hemoglobin A1c (HbA1c) when measured using the enzymatic HbA1c assay reagent Norudia N HbA1C in patients with low catalase activity. We performed an analytical investigation of an improved reagent, (RE) Norudia N HbA1c, which has been developed to lower the rate of obtaining falsely high levels, using an EV800 Clinical Analyzer. For within-run reproducibility, the coefficient of variation was from 0.42% to 0.68%. NGSP exhibited a linear dilution from 3.16% to 17.64%. The accuracy was from 98.4% to 101.4%. On-board stability was favorable up to 28 days. HbA1c levels were not affected by free bilirubin (up to 50 mg/dL), conjugated bilirubin (up to 50 mg/dL), formazin turbidity (up to 3,000 FTU), or ascorbic acid (up to 50 mg/dL). Correlation of (RE) Norudia N HbA1c with Norudia N was high, with a correlation coefficient of 0.998 (n = 56). The regression equation was y = 1.000x + 0.010, and no extremely large deviations among samples were found. From the results presented above, the analytical performance of (RE) Norudia N was found to be favorable. The two samples that yielded falsely high HbA1c levels measured using Norudia N did not reveal any significant difference in HbA1c level between (RE) Norudia N and other enzymatic assay reagents, suggesting that (RE) Norudia N suppressed falsely high HbA1c levels. The analytical performance of (RE) Norudia N is favorable, and it lowers the rate of obtaining falsely high HbA1c levels, making it useful for routine testing.
