Influence of methodology on glycosylated hemoglobin values in Nigerian subjects with sickle cell hemoglobinopathy

The determination of glycosylated hemoglobin (GHb) has been found useful in the medium term assessment of diabetic control. Levels of GHb have been shown to be influenced by hematological abnormalities and methodology amongst other factors. Hemoglobinopathies are common in Nigerians and other people of African descent. No work, to our knowledge, has been done in Nigeria to study the effect of hemoglobinopathies on the levels of GHb in Nigerians or Africans. In this study, GHb levels in non-diabetic Nigerians (with hemoglobin genotypes AA, AS, and SS) were determined by short column chromatography and thiobarbituric acid colorimetry. Levels of GHb obtained by the microchromatographic method were significantly different from one another in the three subject groups. The group mean GHb level was highest in subjects with sickle cell anaemia and lowest in subjects with sickle cell trait. However, using the colorimetric method, the mean GHb level of the normal subjects with hemoglobin genotype AA was not significantly different from that of subjects with hemoglobin genotype AS or SS. Results of GHb determinations by microchromatography (for which several commercial kits are available) in subjects with sickle cell anemia or trait must be interpreted with caution. The colorimetric method, though more tedious, gives more reliable results and should be the method of choice in subjects with concurrent diabetes and sickle cell anemia or trait.