The effect of hemoglobin F upon glycosylated hemoglobin determinations

Glycosylated hemoglobin (Hgb A1) determinations have been advocated for monitoring the control of diabetes mellitus. The prevalent method today for measuring Hgb A1 for most clinical laboratories has been a "mini-column" utilizing ion exchange chromatography. It has been stated that hemoglobin F (Hgb F) will elute with Hgb A1 and interfere with Hb A1 determinations. This study was designed to determine the quantitative effects of Hgb F upon Hgb A1 determinations. Thirty per cent of the study group had elevated Hgb A1 levels at 2% Hgb F concentration, 66% at 3% Hgb F concentration, and all individuals had elevated Hgb A1 levels at Hgb F concentrations of 4% or greater. The relationship of Hgb F to Hgb A1 concentration was not a simple identity, but could be represented by the equation y = 6.03 + 1.24x. If the ion exchange chromatography methodology is used, Hgb F levels should be determined whenever Hgb A1 levels are elevated, particularly in populations where increased Hgb F levels also might be encountered. The authors determined Hgb F levels whenever the concentration of Hgb A1 was 10% or greater. In their population, they found that approximately 1.5% of samples with elevated Hgb A1 concentrations had increased (greater than 2%) Hgb F levels.