Determination of glycosylated hemoglobins in neonatal blood by isoelectric focusing.

Isoelectric focusing (IEF) with suitable "spacers" can be used to distinguish glycosylated hemoglobins from HbA and HbF in adults and infants, respectively. Using this technique we have shown that there is a good correlation between glycosylated hemoglobins measured by IEF and column chromatography (r = 0.778, P less than 0.001). There was no significant difference in the rate of glycosylation between adult and cord blood hemolysates following incubation with glucose in vitro: In both instances there was an increase from the normal levels of about 5% to 26% through 31% after 18 hours of incubation. The levels of glycosylated hemoglobins in infants of varying gestation, neonates, and normal adults was remarkably constant, varying from 4.7 +/- 1.1% to 6.1 +/- 1.6%. These results show that IEF can be useful in the quantitation of glycosylated hemoglobins, particularly in the presence of hemoglobins (eg, HbF) where standard chromatographic techniques cannot be used. IEF has the added advantage of using small quantities of blood, and allows a number of samples to be tested at the same time, thus facilitating the identification of abnormal hemoglobins.