Comparison of three different assay procedures for the determination of HbA1 with special attention to the influence of pre-HbA1c, temperature and haemoglobin concentration.

Three different methods for the measurement of glycated haemoglobin or HbA1, based on agar gel electrophoresis, ion-exchange and affinity chromatography were compared. All three showed acceptable precision (overall CV being less than 5%) and correlated well with each other (r greater than 0.945). The ion-exchange and affinity chromatography method proved to be independent of the amount of pre-HbA1c present. The electrophoresis method was independent of temperature in contrast to the other two methods, which showed a strong and comparable temperature dependency. All three methods were dependent on the haemoglobin concentration and/or protein content of the haemolysate. Both ion-exchange and electrophoresis showed significant interference by changes in haemoglobin concentrations, whereas the protein concentration significantly biased the affinity chromatography figures. Taking into account their specific merits all three methods are acceptable for routine use.