Haemoglobin A1c measurement in patients with chronic kidney disease

Objectives: The aim of this study is to investigate the interference of carbamylated haemoglobin (cHb) to haemoglobin A(1c) (HbA(1c)) measurements in patients with chronic kidney disease (CKD) by three ion-exchange chromatography methods. Design and methods: We included three ion-exchange chromatography methods (Bio-Rad Variant II, G7 and HA-8160) and one affinity chromatography method (Primus Ultra2) to test HbA(1c). In vitro carbamylation of haemoglobin was also performed to test interference of carbamylation. Results: 152 CKD patients were diagnosed. The average HbA(1c) and urea levels of nondiabetic and diabetic patients were 5.24% (33.8 mmol/mol) and 7.36% (56.9 mmol/mol) and 16.2 mmol/L and 11.2 mmol/L, respectively. Repeated measures ANOVA showed that the difference of HbA(1c) values between four methods is not statistically significant (P = 0.421 for non-DM and P = 0.336 for DM). With the increase in blood urea concentration from stage 3 to stage 5, there was no corresponding increase in HbA(1c) values for both groups. In vitro carbamylation results showed that carbamylated Hb peaks could be clearly identified by the three ion-exchange methods. Conclusion: HbA(1c) measurement by these methods may not be impacted by carbamylated Hb. The results should be interpreted with caution in high carbamylated Hb patients. (C) 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.