Hemoglobin Variant Frequency Detected during a Comprehensive Medical Examination in Japan at GENKI PLAZA MEDICAL CENTER FOR HEALTH CARE

Abstract

 Hemoglobin A1c (HbA1c) is a tool widely used to diagnose or monitor long-term glycemic control in diabetic patients. However, there are hemoglobin (Hb) gene variants or modifications that may affect the accuracy of the A1c value yielding a false high or false low A1c result. HbA1c measurements were performed on an ion exchange HPLC instrument Tosoh HLC-723G11 automated analyzer [Standard mode]. Chromatograms were reviewed for 104,316 samples run in the months of August 2016 to July 2017. All the samples came from a comprehensive medical examination. A total of 43 samples were visually inspected for abnormal patterns suggesting the presence of hemoglobin variants. With support of Tosoh Corporation, all 43 samples underwent additional investigation on the conventional HPLC system with a 40 minute elution time in order to determine the Hb Variant. Based on the results of the additional investigation a total of 43 suspected variants were classified into 4 groups (A~D) according to the chromatographic pattern. Comparison to the results between the G11 and the Affinity Mode additional testing, the G11 showed 38 False low results (88.4%) and 5 False high results (11.6%). Since the result of the additional investigation suggests an interference of the hemoglobin variants in a total of 43 samples, a detection ratio of the hemoglobin variant in this population is 0.041%. It is important to have a better understanding of the HPLC method and characteristics of the variant samples on the method. Also routine inspection of the chromatogram for abnormal peaks, high HbF result and balance compared to related chemistry or hematology testing by the technician will improve the quality and accuracy of the report.