Abstract
Variant hemoglobin may lead to errors in assessing glycemic control due to abnormal HbA1c values. We herein report five patients with variant hemoglobin that was discovered based on abnormally low HbA1c values (<4.2 %) during routine medical examinations. In patients with abnormally low HbA1c values measured using the high-pressure liquid chromatography (HPLC) method (HPLC-HbA1c), the glycated albumin (GA) and HbA1c levels were measured using an immunoassay (IA-HbA1c). All five nondiabetic patients with a discrepancy between the HPLC-HbA1c values and the GA and IA-HbA1c values had a heterozygous mutation in the β-globin chain (Hb Shizuoka in one patient, Hb Moriguchi in two patients and Hb G-Szuhu in two patients). Therefore, in cases of abnormally low HPLC-HbA1c levels that are discrepant with the GA and IA-HbA1c levels, a diagnosis of variant hemoglobin should be strongly suspected. We also present a flowchart that we use to diagnose variant hemoglobin in patients with abnormally low HPLC-HbA1c values.
