Consistently elevated HbA1c seen with HPLC testing, but not with immunoassay
WEDNESDAY, Aug. 26, 2015 (HealthDay News) — Type 2 diabetes can be misdiagnosed in patients with hemoglobin (Hb) Wayne, according to a case report published online Aug. 20 in Diabetes Care.
Elona Turley, M.D., from the University of Alberta in Edmonton, Canada, and colleagues describe the case of a 66-year-old Caucasian female who was referred for specialist follow-up of treatment-refractory type 2 diabetes, which was diagnosed based on two consecutive HbA1c results >6.5 percent. The patient had glycemic control that was difficult to manage, with persistently elevated HbA1c despite treatment with metformin and insulin glargine; she began to experience symptoms of episodic hypoglycemia with treatment.
The researchers note that suspicion of interference was triggered by a fasting glucose of 84.6 mg/dL obtained at the same time as an HbA1c of 11.2 percent. The HbA1c analysis was repeated by immunoassay rather than high-performance liquid chromatography (HPLC; VARIANT II TURBO HbA1c Kit – 2.0; BioRad) and a result of 5.2 percent was obtained. The presence of the α-globin chain mutant Hb Wayne was identified on hemoglobinopathy investigation. Hb Wayne has been reported to interfere with Bio-Rad VARIANT II HPLC HbA1c measurements. Measurement of HbA1c with immunoassay is more accurate as it uses antibodies to recognize the structure of the β-N-terminal glycated amino acid.
“Like all laboratory tests, HbA1c measurement is subject to interferences, and results must be interpreted within the clinical context,” the authors write.
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