Fully automated assay of glycohemoglobin with the Abbott IMx analyzer: novel approaches for separation and detection

We describe a novel assay for measuring glycohemoglobin directly from anticoagulated whole blood with the Abbott IMx analyzer. The glycohemoglobin is labeled with a soluble polyanionic affinity reagent and the anionic complex is then captured with a cationic solid-phase matrix. Glycohemoglobin is quantified by measuring the quenching by heme of the static fluorescence from an added fluorophore. The assay is standardized to report both percent total glycohemoglobin (%GHb) and percent hemoglobin A1c (%HbA1c). Glucose, bilirubin, triglycerides, labile fraction, and hemoglobin variants do not interfere in the assay. Within- and between-run CVs are approximately 4-5%, with total CVs of approximately 6.5%. Highly significant linear correlations (r > 0.97) were obtained in comparison studies with two major assay methodologies. The time to obtain one result is approximately 10 min (including assay of a control), 56 min for 22 results. We describe the development, standardization, and validation of this new method.