[Assay of glycosylated hemoglobin by agar gel electrophoresis in an acid pH. Value of the determination of the stable fraction in clinical biology].

Total glycosylated haemoglobin (Hbg) has been determined by electrophoresis on agar gel, using commercially available materials. This method is simple and unaffected by changes of temperature or buffers pH. With a performing densitometer, its coefficient of variation is less than 4% within batch, less than 6% between batch. There is a significant correlation with the small column separation technique (r = 0,93; p less than 0,001). The labile glycosylated haemoglobin is removed by 5 methods: 18 hrs dialysis of haemolysate at 4 degrees C; 30 mn incubation of whole-blood with semi-carbazide and aniline at pH 5 and 37 degrees C; 6 hrs saline incubation of erythrocytes at 37 degrees C; 18 hrs saline incubation of erythrocytes at 25 degrees C; 7 days storage at 4 degrees C. The two first methods appear to be the best. In our study we can conclude that: 1) In basal conditions the size of the labile fraction of Hb g was close to the limits of variability of the methods (less than or equal to 10%). 2) Therefore, except for brittle diabetics, it is not necessary to determine the labile fraction routinely.