Hb E1c as an Indicator for the Presence of Hb AE Phenotype in Diabetic Patients

Abstract

Since the observation of a “fast-moving” hemoglobin (Hb) in diabetic blood specimens by Rahbar in 1968 (1) and the subsequent structural identification of the glucose-“modified” Hb (2), the measurement of erythrocyte glycoHb (Hb A1c) has served as the monitor for long-term glucose control for patients with diabetes mellitus (3). Column chromatography was one of the first methodologies used for the quantification of Hb A1c (4). Recent modifications of the methodology, including shorter column size and faster turnaround time, have resulted in the application of automated HPLC for Hb A1c analysis. As column chromatography has always been a major tool for the investigation of human Hb variants, the use of automated HPLC systems for the analysis of Hb A1c in clinical laboratories renders an extra opportunity for detecting abnormal Hbs in clinical blood specimens, e.g., Hb Manitoba, Hb G-Coushatta, Hb Turriff, and Hb Sherwood Forest (5)(6)(7). The presence of an abnormal Hb will result in the formation of its own minor glycoHb; the total glycoHb in the red cells of a Hb variant trait carrier is then the sum of the glycoHb A and the glycoHb variant. For example, the total glycoHb in a sickle cell trait carrier (Hb AS) is Hb A1c Hb S1c. We describe in this report the chromatographic property of the minor glycoHb E (α2β226Glu→Lys) in an automated HPLC system, and the usefulness of the detection of the Hb E1c peak in the HPLC chromatogram as the indicator for the presence of Hb E in the patient. This study involved EDTA whole-blood specimens specifically for Hb A1c analysis. Hospital in-house specimens arrived in the authors’ NUH Referral Laboratories within 2 h, whereas referral samples were delivered overnight by courier. The …