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.

In this two-step automated assay of the MB isoenzyme of creatine kinase (CK-MB), developed for the Abbott "IMx" immunoassay analyzer, monoclonal anti-CK-MB antibody immobilized onto latex microparticles and polyclonal anti-CK-MM antibody coupled to alkaline phosphatase are used. Within-run CVs ranged from 3.9% to 9.0%, between-run CVs from 0.0% to 5.6%, and the sensitivity was 0.2 microgram/L. Twenty-four results can be obtained in about 37 min. Analytical recovery of CK-MB added to human serum or plasma ranged from 89% to 109%. Icteric, lipemic, or hemolyzed samples did not interfere with CK-MB recovery. Cross-reactivity with CK-MM and CK-BB was 0.012% and 0.001%, respectively. The normal reference interval was 0-5 micrograms/L. IMx CK-MB results correlated well with CK-MB enzyme activity as determined by electrophoresis (n = 203; r = 0.97; slope = 0.90; y-intercept = -4.29) and with commercial immunoassays. We think that this assay will be useful for confirmation of acute myocardial infarction, both in critical-care units and in the clinical laboratory.

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