title: Estimation of biological variation and reference change value of glycated hemoglobin (HbA(1c)) when two analytical methods are used.
abstract: OBJECTIVE
  Available data on biological variation of HbA1c revealed marked heterogeneity. We therefore investigated and estimated the components of biological variation for HbA1c in a group of healthy individuals by applying a recommended and strictly designed study protocol using two different assay methods.
  
  
  METHODS
  Each month, samples were derived on the same day, for three months. Four EDTA whole blood samples were collected from each individual (20 women, 9 men; 20-45 years of age) and stored at -80°C until analysis. HbA1c values were measured by both high performance liquid chromatography (HPLC) (Shimadzu, Prominence, Japan) and boronate affinity chromatography methods (Trinity Biotech, Premier Hb9210, Ireland). All samples were assayed in duplicate in a single batch for each assay method. Estimations were calculated according to the formulas described by Fraser and Harris.
  
  
  RESULTS
  The within subject (CV(I))-between subject (CV(G)) biological variations were 1.17% and 5.58%, respectively for HPLC. The calculated CV(I) and CV(G) were 2.15% and 4.03%, respectively for boronate affinity chromatography. Reference change value (RCV) for HPLC and boronate affinity chromatography was 5.4% and 10.4% respectively and individuality index of HbA(1c) was 0.35 and 0.93 respectively.
  
  
  CONCLUSIONS
  This study for the first time described the components of biological variation for HbA1c in healthy individuals by two different assay methods. Obtained findings showed that the difference between CV(A) values of the methods might considerably affect RCV. These data regarding biological variation of HbA(1c) could be useful for a better evaluation of HbA(1c) test results in clinical interpretation.
authors.affiliation: Department of Clinical Biochemistry, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ankara, Turkey. Electronic address: drfucar@gmail.com.
authors.forename: Fatma
authors.initials: F
authors.lastname: Ucar
authors.forename: Gonul
authors.initials: G
authors.lastname: Erden
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Ginis
authors.forename: Gulfer
authors.initials: G
authors.lastname: Ozturk
authors.forename: Sevilay
authors.initials: S
authors.lastname: Sezer
authors.forename: Mukaddes
authors.initials: M
authors.lastname: Gurler
authors.forename: Ahmet
authors.initials: A
authors.lastname: Guneyk
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D015925:Cryopreservation; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: Biological variation; Glycated hemoglobin; Reference change value