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.