Proportion of glycosylated hemoglobin in erythrocytes of a person with hemoglobins A, S, and G Philadelphia.

The apparent proportion of column-chromatographically measured glycosylated hemoglobin in erythrocytes from an individual with hemoglobins A, S, and G was only 2.3% because the slow glycosylated variant hemoglobins were retarded in the column. In contrast, the value for glycosylated hemoglobin was 7.8% by a new cellulose acetate electrophoretic method that includes use of dextran sulfate buffer. The erythrocyte metalloprotein, carbonic anhydrase B, was shown to co-migrate with glycosylated hemoglobin by this technique, however. Thus carbonic anhydrase B, HbF, and HbA all have weak attraction for negative charges at acid pH. We believe that carbonic anhydrase B should contribute significantly (at least 10-20% absorbance) to the HbA1 by this electrophoretic method. We conclude that microcolumn chromatography should remain the method of choice for HbA1 determination, that subject-based reference intervals should be used for HbS or HbC heterozygotes, and that electrophoretic HbA1 methods should be reserved for use with both HbS and HbC homozygotes and HbSC disease.