Impact of heterozygous hemoglobin E on six commercial methods for hemoglobin A1c measurement

Background: This study examined the impact of heterozygous HbE on HbA1c measurements by six commonly used commercial methods. The results were compared with those from a modified isotope-dilution mass spectrometry (IDMS) reference laboratory method on a liquid chromatograph coupled with tandem mass spectrometer (LC-MS/MS). Methods: Twenty-three leftover samples of patients with heterozygous HbE (HbA1c range: 5.4–11.6%), and nineteen samples with normal hemoglobin (HbA1c range: 5.0–13.7%) were included. The selected commercial methods included the Tina-quant HbA1c Gen. 3 (Roche Diagnostics, Basel, Switzerland), Cobas B 101 (Roche Diagnostics, Basel, Switzerland), D100 (Bio-Rad Laboratories, Hercules, CA, USA), Variant II Turbo HbA1c 2.0 (Bio-Rad Laboratories, Hercules, CA, USA), DCA Vantage (Siemens Healthcare, Erlangen, Germany) and HbA1c Advanced (Beckman Coulter Inc., Brea, CA, USA). Results: With the exception of Cobas B 101 and the Variant II Turbo 2.0, the 95% confidence intervals of the Passing–Bablok regression lines between the results from the six commercial methods and the IDMS method overlapped. The latter suggested no statistically significant difference in results and hence no impact on HbA1c result despite the presence of heterozygous HbE. The method of Cobas B 101 gave positive bias at the range of concentrations examined (5.4–11.6%), while that of Variant II Turbo 2.0 gave positive bias at concentrations up to approximately 9.5%. The finding of significant positive bias in the methods of Cobas B 101 and Variant II Turbo 2.0 agrees with the observations of some previous studies, but is contrary to manufacturer’s claim indicating the absence of interference by heterozygous HbE. Our results also clearly showed the impact of heterozygous HbE across a fairly broad measurement range using a laboratory method (the Variant II Turbo 2.0). Laboratory practitioners and clinicians should familiarize themselves with prevailing hemoglobin variants in the population they serve and select the appropriate methods for HbA1c measurement. How to cite this article Yong S, Liu H, Lum CLT, Liu Q, Sim SY, Chay FFM, Cheng WL, Neo SF, Chew S, Ong L, Loh TP, Liu Q, Teo TL, Sethi SK. 2021. Impact of heterozygous hemoglobin E on six commercial methods for hemoglobin A1c measurement. PeerJ Analytical Chemistry 3:e9 DOI 10.7717/peerj-achem.9 Submitted 25 September 2020 Accepted 19 January 2021 Published 23 March 2021 Corresponding author Tze Ping Loh, tploh@hotmail.com Academic editor Pawel Urban Additional Information and Declarations can be found on page 8 DOI 10.7717/peerj-achem.9 Copyright 2021 Yong et al. Distributed under Creative Commons CC-BY 4.0 Subjects Analytical Chemistry (other)