Influence of Hemoglobin Strasbourg, a Rare High Oxygen Affinity Hemoglobin Variant, on Different Methods of HbA1c Measurement

Hemoglobin Strasbourg is a rare high oxygen affinity hemoglobin variant which leads to secondary erythrocytosis. This variant is caused by a HBB gene mutation c.71T > A resulting in an amino acid exchange on position 23 of the beta globin chain (p.Val23Asp.). The influence of Hb Strasbourg on HbA1c measurement has not been studied to date. For patients with hemoglobin variants it is important to know whether possible interferences exist with the measurement of HbA1c. We therefore investigated the influence of Hb Strasbourg on HbA1c measurement with two different HPLC (high-performance liquid chromatography) systems and one turbidimetric immunoassay in two non-diabetic brothers who are heterozygous carriers of Hb Strasbourg. The examined tests are all used in routine diagnostics. In the case of Hb Strasbourg, the HbA1c measured by HPLC showed lower results than those obtained by the immunoassay. We conclude that HbA1c is underestimated when measured with these methods as glycated Hb Strasbourg is most likely not co-eluting with HbA1c in HPLC.