Screening for hemoglobinopathies during routine hemoglobin A1c testing using the Tosoh G7 Glycohemoglobin Analyzer

Approximately 5.1% of the US population has diabetes mellitus, and hemoglobin (Hb) A1c levels are routinely measured to monitor long-term glycemic control in these patients. Many laboratories use ion exchange chromatography for such measurements, and the presence of hemoglobin variants and hemoglobinopathies often results in abnormal peaks on the chromatogram. The goal of this study was to evaluate the potential that detection of these abnormal peaks provides as a screening tool for Hb variants and hemoglobinopathies. We examined 366 specimens with abnormal peaks observed during routine Hb A1c measurements using the G7 Glycohemoglobin Analyzer (Tosoh Bioscience, Inc.). Hb variants and hemoglobinopathies were characterized by alkaline and acid electrophoresis, solubility testing for Hb S, and clinical parameters. In 252 cases, sickle cell trait was identified with a mean retention time (RT) of 1.44 (SD +/-0.02) min. In 82 cases, Hb C trait was identified with a mean RT of 1.66 +/-0.03 min. RTs for other Hb abnormalities, including sickle cell disease, homozygous Hb C disease, C Harlem trait, alpha-chain Hb variants, Hb D trait, Hb G trait, Hb J trait, Hb Raleigh, and Hb Lepore were also determined. Our results demonstrate that routine Hb A1c testing provides a potential screening tool for the detection of common hemoglobin variants and hemoglobinopathies. The previously unreported RTs for the G7 Glycohemoglobin Analyzer are provided, which can facilitate further testing in previously undiagnosed patients and confirm the cause of abnormal peaks in patients with known hemoglobin abnormalities.