Quality Control and Quality Requirements for the Measurement of Glycated Hemoglobin

Abstract

In the follow-up of the treatment of diabetes mellitus the determination of glycated blood proteins, especially blood hemoglobin, has been proved to be very important in estimation of the long-term balance of the disease. Many methods have been developed, but its seems quite evident that the HPLC-methods which measure the proportion of glycated hemoglobin Alc (GHbAlc) or the affinity chromatography measuring all glycated forms of hemoglobin (GHb) are the most useful for the routine clinical laboratory work (1,2,3,5). There are many difficulties in organizing the quality control of the determination of glycated hemoglobin. First problem e.g. in Finland is that there are at least six commercial methods in use. In Table 1 there are presented the methods and their reference intervals for the determination of glycated hemoglobins. The second is the measurement temperature, which must be know when the values for glycated hemoglobins has been calculated by using minicolumn techniques. The best way is to perform the columnphase in a thermostated water bath. The third and perhaps the most difficult problem is to find the ideal control material which fulfills the criteria: the control material should be identical with patient samples, the concentration of the analyte should be at the desired level and the stability of the control material should be long enough. In the university central hospital district of Kuopio we have selected an automated HPLC-method and measured GHbAlc values for the whole district. Today we have two different instruments for the measurement of GHbAlc: the older one (3) is the FPLC-system (Pharmacia, Uppsala, Sweden) and the newer one an HPLC-instrument of Shimadzu (6) with an strong ion-exchange