Introduction: Few data are available on the alignment of the different methods used for HbA(2) quantitation and recent external quality survey results show a consistent spread of HbA(2) values. To this aim, a comparison study among the actual best performing techniques for HbA(2) determination, comprising HPLC and CE methods, was performed.
Methods: A total of 80 blood samples collected from normal subjects and β-thalassemia carriers were analyzed by different HPLC (Bio-Rad Variant I, Bio-Rad Variant II, Menarini HA-8160, Tosoh G7, Tosoh G8) and capillary electrophoresis (Beckman Coulter MDQ and ProteomeLab PA 800, Sebia Capillarys 2) methods. Patient's samples with clinically relevant hemoglobin variants (HbC, HbD, HbE, HbS, and δ-chain variants) were also tested by all methods.
Results: The mean within-run imprecision of HbA(2) measurement (expressed as CV, %) was between 0.5% and 4.4% (HPLC) and between 1.2% and 4.4% (capillary electrophoresis). The comparison study showed that the different methods were highly correlated (r between 0.974 and 0.997) although biased each other. HbA(2) determination in presence of abnormal hemoglobins was variously interfered by both HPLC and CE methods. Concerning HbF, the mean imprecision at HbF values ≥1.5% was between 1.2% and 8.2% (as CVs).
Conclusions: A poor alignment of routine methods for HbA(2) measurement was found. The need of a better standardization of HbA(2) measurement procedures was underlined.
© 2012 Blackwell Publishing Ltd.