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Evaluation of Conditions Associated with Glycated Hemoglobin Values below the Reference Range by Wolfgang J. Schnedl, Theresa Lahousen, Robert Krause, Sandra J. Wallner, Claudia Piswanger-Soelkner, Rainer W. Lipp

Background – Evaluation of conditions associated with glycated hemoglobin (HbA1c) values below the reference range in HbA1c determinations.
Methods – Over a time period of 5 years, HbA1c results were determined with the ion-exchange high-performance liquid chromatography (HPLC) method HA-8140 Menarini.
Results – Of approximately 20 000 HbA1c results analyzed, 9 were below the reference range. The reason for HbA1c values below the reference range was found to be liver cirrhosis in 6 patients, anemia with hematological neoplasms in 2 patients, and elevated fetal hemoglobin >1.5% in one patient. The silent hemoglobin (Hb) variant Hb Graz in 6 patients, Hb Sherwood Forest in 1 patient, homozygote HbS in one patient, and gross hypertrigly- ceridemia in one patient demonstrated no HbA1c result.
Conclusions - In patients with liver cirrhosis, HbA1c measurements should be used with caution when evaluating long-term glucose control, and samples with suspected Hb variants should be analyzed by hemoglobin electrophoresis. Our study underscores the need for clinical laboratories and physicians to be aware of the limitations of their HbA1c assay methods as well as of the importance of visual inspection of ion-exchange chromatograms to detect HbA1c values below the reference range and abnormalities caused by the interference factors described here.

DOI: Clin. Lab. 2007;53:179-181