Influence of hemoglobin variants and derivatives on glycohemoglobin determinations, as investigated by 102 laboratories using 16 methods.
Influences of hemoglobin (Hb) variants (HbSS, HbCC, beta-thalassemia, HbAE, HbAS, HbAC, hereditary persistent HbF) and Hb derivatives (carbamylated- and acetylated-Hbs, Schiff base, and those formed in stored blood) on results of glyco-Hb assays by 102 laboratories using 16 different methods were investigated. Affinity chromatography shows deviating results only with homozygous Hb S and C. Correct interpretation of results from patients with decreased erythrocyte half-lives requires previous knowledge on this condition. Measurements of HbA1c by HPLC and electrophoresis are obviously unsuitable for homozygous hemoglobinopathies; for heterozygous hemoglobinopathies and Hb synthesis variants, HbA1c should be expressed as percentage of HbA0 + HbA1c; abnormal Hbs are usually recognized; both carbamylated- and acetylated-Hbs interfere and Schiff base must be eliminated. Except for stored blood, all Hb variants and derivatives gave erroneous results with disposable ion-exchange columns. Dako's immunoassay is not affected by Hb derivatives; glycated Hb variants are not recognized as glyco-Hb and percentages are consequently too low. Glyco-Hb by the immunoassay of Bayer (performed by one laboratory) is not affected by Hb variants and derivatives.
Weykamp
C W
CW
Department of Clinical Chemistry, Queen Beatrix Hospital, Winterswijk, The Netherlands.
Penders
T J
TJ
Muskiet
F A
FA
van der Slik
W
W
D002624:Chemistry, Clinical / Q000379:methods*; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D004586:Electrophoresis; D005319:Fetal Hemoglobin / Q000032:analysis; D006442:Glycated Hemoglobin / Q000032:analysis*; D006444:Hemoglobin C / Q000032:analysis; D006446:Hemoglobin E / Q000032:analysis; D006451:Hemoglobin, Sickle / Q000032:analysis; D006453:Hemoglobinopathies / Q000097:blood; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007118:Immunoassay; D011786:Quality Control; D012016:Reference Values; D017086:beta-Thalassemia / Q000097:blood
D005319:Fetal Hemoglobin; D006442:Glycated Hemoglobin; D006444:Hemoglobin C; D006446:Hemoglobin E; D006451:Hemoglobin, Sickle; D006455:Hemoglobins, Abnormal; C076696:hemoglobin AC; C028671:hemoglobin AS