title: Impact of carbamylation on three different methods, HPLC, capillary electrophoresis and TINIA of measuring HbA1c levels in patients with kidney disease.
abstract: OBJECTIVE
  Aim of this study was to investigate whether established IFCC traceable routine measurements of HbA1c levels in patients with kidney diseases result in comparable and valid results. Additionally, the influence of carbamylation as a marker of uremia on the measurement methods was assessed.
  
  
  METHODS
  We compared three different measurement methods (high-performance liquid chromatography (HPLC), capillary electrophoresis and turbidimetric inhibition immunoassay (TINIA)) based on 407 nephrology samples for HbA1c determination with specific analysis of the threshold areas where different HbA1c measurements could result in different diagnoses (diabetes mellitus vs prediabetes and prediabetes vs non-diabetes). Indirectly, a potential effect of carbamylated hemoglobin was assessed based on determination of BUN levels in serum.
  
  
  RESULTS
  In nephrological samples, we were able to show that three different measurement methods provide similar results regarding HbA1c in routine diagnostics. Our results show that with BUN concentrations <80 mg/dl and ≥80 mg/dl, similar HbA1c levels were determined, independent of measurement method.
  
  
  CONCLUSIONS
  While routine measurements follow IFCC standards, many interfering factors remain which can influence HbA1c determination, e.g. carbamylation of proteins. As kidney disease is the most common complication in patients with diabetes mellitus, interference in the measurement of HbA1c due to carbamylated proteins as markers of uremia must be recognized and if necessary corrected. We found not only a weak influence of carbamylation on all methods of HbA1c determination, but also that, in nephrological samples, the three different measurement methods provided similar results regarding HbA1c in routine diagnostics.
authors: Department of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany. Electronic address: ramona.dolscheid-pommerich@ukb.uni-bonn.de.
authors: Ramona C
authors: RC
authors: Dolscheid-Pommerich
authors: Department of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany.
authors: Sonja
authors: S
authors: Kirchner
authors: Department of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany.
authors: Carola
authors: C
authors: Weigel
authors: Department of Anesthesiology and Intensive Care Medicine, University Clinics Bonn, Germany.
authors: Lars
authors: L
authors: Eichhorn
authors: Department of Psychosomatic and Medicine and Psychotherapy, University Clinics Bonn, Germany.
authors: Rupert
authors: R
authors: Conrad
authors: Department of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany.
authors: Birgit
authors: B
authors: Stoffel-Wagner
authors: Department of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany.
authors: Berndt
authors: B
authors: Zur
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006441:Hemoglobin A / Q000031:analogs & derivatives; D006801:Humans; D007674:Kidney Diseases / Q000097:blood*; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods*
chemical_list: D006442:Glycated Hemoglobin; D006441:Hemoglobin A; C022017:hemoglobin A, carbamylated
keywords: Carbamylation; Diabetes mellitus; HbA1c; Kidney disease; Nephrology