Direct enzymatic assay for %HbA1c in human whole blood samples

Objectives: Development and validation of a direct enzymatic HbA1c assay that utilizes a single channel on chemistry auto-analyzers without the need to run separate glycated hemoglobin and total hemoglobin assays. Design and methods: An enzyme based single channel assay was developed to measure %HbA1c in human whole blood samples. The performance characteristics of the Diazyme Direct Enzymatic HbA1c Assay were evaluated on the Hitachi 917 auto-analyzer using whole blood samples, appropriate controls and a reference lot of manufactured reagents. Accuracy studies were completed by comparing the Direct Enzymatic Assay to existing HPLC and immunoassay methods. Interference testing was performed to determine the effect of total hemoglobin, glycated serum proteins, chemical substances and hemoglobin variants in patient samples. Results: The Direct Enzymatic HbA1c Assay showed within run precision and total precision results of <= 2% CV for both normal and abnormal level samples. Method comparison studies showed that there was a good correlation between the Direct Enzymatic HbA1c and the HPLC (R-2=0.98) or the immunoassay (R-2=0.97) methods. The assay measured within the range of 4-16% HbA1c and showed excellent performance with variant hemoglobin in samples. Conclusions: Diazyme Direct Enzymatic HbA1c Assay is accurate and precise when compared to currently marketed medical devices. The assay is designed to report %HbA1c values directly without need for a separate measurement of total hemoglobin and is not adversely affected by interferences from common hemoglobin variants in samples. It is a cost effective, user-friendly method and is adaptable to most general chemistry analyzers. (c) 2008 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.