A Novel Aberrant HbF Peak with Electrophoretic Shift in A1c of a Patient with Chronic Lymphocytic Leukemia (CLL) Was Reversible to Give Interpretable Results

<b>Background</b>: A strikingly unusual pattern with a possible up-field shift in Hemoglobin A1c (HbA1c) and A0 (HbA0) peaks and an unexplained hemoglobin F (HbF) peak with capillary electrophoretic shift in the HbA1c chromatograms of a leukemia patient were found while performing a HbA1c screen. <b>Methods</b>: A review of the patient's history with an exhaustive search of the literature ruled out medications as interfering factors or contributing to the abnormal findings. Other than hyperleukocytosis, the patient did not have the aberrant HbF peak noted previously in the electrophoresis or contributing factors. We hypothesized that the irregular chromatographic pattern and wrong location of the HbA1c peak, hereafter referred to as the downfield shift in the electrophoretic species, was due to various glycation or fructosamine adducts and derivatives within the HbA1c and A0 protein. <b>Results</b>: A literature search offered little guidance. However, the instrument troubleshooting measures suggested a hemoglobin variant or exogenous transfusion as a putative source for the HbF peak, while the downfield shift in the chromatogram remained unexplained.