Automated determination of glycated hemoglobin: comparative evaluation of five assay systems.

We evaluated four newly introduced assays for determination of glycated hemoglobin allowing the processing of large amounts of samples in a clinical routine laboratory. These methods were compared to the Bio-Rad Diamat system. The investigated methods were the Merck Hitachi L-9100, a fully automated HPLC analyser, the Abbott IMx glycated hemoglobin ion capture assay, the DAKO HbA1c enzyme linked immunosorbent assay (ELISA), and the Boehringer-Mannheim HbA1c Tinaquant turbidimetric assay. All methods showed generally acceptable precision and good accordance with the Diamat system. Interference study showed influence of anaemia, polycythemia, rheumatoid factor, and chronic hemodialysis on the values of the DAKO ELISA and of anaemia and polycythemia on the values of the Boehringer-Mannheim Tinaquant assay. All of the investigated methods allow referring of results either as measured or standardized HbA1c values, the latter obtained after calibration with reference to an ion exchange high-pressure liquid chromatography method. Our data confirm the feasibility of this kind of standardisation of glycated hemoglobin assays, allowing direct comparison of results from various determination methods.