Clinical Information

This assay is not useful in determining day-to-day glucose control and should not be used to replace daily home testing of blood glucose. The presence of hemoglobin variants can interfere with the measurement of hemoglobin A1c (HbA1c). The advantage of using ion exchange chromatography methods is most variants that would affect HbA1c results can be detected from analysis of the chromatogram so inaccurate results are less likely to be reported. Many common hemoglobin (Hb) variants (HbF <30%, heterozygous HbE, heterozygous HbD, heterozygous HbC, heterozygous HbS) do not interfere with this method. Other Hb variants that do show interference with this method include, but are not limited to Hb Camperdown, Hb Fukuoka, Hb Philadelphia, Hb Wayne, and Hb Raleigh. In patients with rare homozygous and double heterozygous forms of abnormal Hb (e.g., CC, SS, EE, SC), there is no HbA present; therefore, no HbA1c value can be determined. If the specimen cannot be analyzed due to a homozygous variant or other interference, measurement of serum fructosamine may be helpful to monitor glycemic control. Some hemoglobinopathies can be associated with reduced red blood cell lifespan and any measured HbA1c concentration would not provide a true measurement of the patient's glycemic control and could lead to misinterpretation. In such situations, fructosamine should be used as an alternate measurement of glycemia and is recommended for monitoring these patients. In cases of hemolytic anemia, the lifetime of erythrocytes is shortened and will result in decreased HBA1c results. This effect will depend upon the severity of the anemia. Specimens from patients with polycythemia or post splenectomy may exhibit increased HBA1c values due to a somewhat longer lifespan of the erythrocytes. Caution should be exercised when interpreting the HbA1c results from patients with these conditions.