title: Interference of the most frequent haemoglobin variants on quantification of HbA1c: comparison between the LC-MS (IFCC reference method) and three routinely used methods.
abstract: OBJECTIVE
  Assaying HbA1c in patients with haemoglobin variants has long been a technical challenge, despite methodological advances that have progressively limited the problem. The purpose of this study was to evaluate the impact of the most frequent haemoglobin variants on three routine separation methods compared with the IFCC reference method.
  
  
  METHODS
  Blood samples from heterozygous patients (AS, AC, AD, AE) were analyzed using the IFCC reference method (LC-MS), and the results compared with those obtained by capillary electrophoresis (CAPILLARYS 2 Flex Piercing, Sebia) and two HPLC methods using cation-exchange (Variant II, Bio-Rad) and affinity chromatography (Ultra(2), Primus).
  
  
  RESULTS
  HbA1c values obtained by the IFCC reference method were comparable to those obtained by the three tested methods whatever the haemoglobin variant. Mean relative biases did not exceed the threshold of 7% (above which differences are generally considered clinically significant), although some individual values were above this limit with Variant II in samples with HbS and for all three methods in samples with HbE.
  
  
  CONCLUSIONS
  This comparative study of the LC-MS reference method and three field methods has demonstrated that these assays are not clinically influenced by the presence of the most common haemoglobin variants. The present results also confirm that the interpretation of HbA1c values in patients with Hb variants remains complex and depends on the assays used and should, in some cases, take into account parameters other than analytical ones (such as differences in glycation rates and half-lives of haemoglobin variants).
authors: Laboratory of Paediatric Biology and Research, American Memorial Hospital, University Hospital of Reims, 47, rue Cognacq-Jay, 51092 Reims cedex, France; Laboratory of Medical Biochemistry and Molecular Biology, FRE CNRS/URCA n(o) 3481, Faculty of Medicine, University of Reims Champagne-Ardenne, Reims, France. Electronic address: sjaisson@chu-reims.fr.
authors: S
authors: S
authors: Jaisson
authors: N
authors: N
authors: Leroy
authors: C
authors: C
authors: Desroches
authors: M
authors: M
authors: Tonye-Libyh
authors: E
authors: E
authors: Guillard
authors: P
authors: P
authors: Gillery
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods; D005189:False Positive Reactions; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000235:genetics*; D006455:Hemoglobins, Abnormal / Q000032:analysis; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*
chemical_list: D006442:Glycated Hemoglobin; D006455:Hemoglobins, Abnormal; C517652:hemoglobin A1c protein, human
keywords: Diabetes mellitus; Diabète sucré; Haemoglobin variants; HbA(1c); Méthode de référence; Reference method; Variants de l’hémoglobine