Misleading Glycated Hemoglobin Results in a Patient with Hemoglobin SC Disease

We encountered a 62-year-old man with hemoglobin (Hb) SC disease. Diabetes mellitus had been previously diagnosed in this patient on the basis of 2 increased fasting glucose values. During an 8-year period, his glycated Hb (GHb) was measured by 3 different methods (Table 1⇓ ), each of which was affected differently by his Hb variants. The GHb results depended more on the method used than on the patient’s mean blood glucose.View this table: Table 1. HbA1c and related measurements over time.The patient’s GHb was measured initially (April 1997) by use of the Roche Hitachi Tina-quant immunoassay. In 2003–2004, we used the Tosoh 2.2 Plus, an assay based on HPLC, which produced chromatograms that were flagged as invalid, so we sent the patient’s samples to a commercial laboratory, which used the Roche Integra …