Is this pathological?

CASE DESCRIPTION A 74-year-old woman with toxic nodular goiter, diabetes mellitus, depression, gastroesophageal reflux disease, and hypercholesterolemia had routine serum protein electrophoresis done for the first time. Her medications included metformin, levothyroxine, sertraline, rosuvastatin, and rabeprazole. The patient’s renal function was normal. Serum protein electrophoresis was carried out by capillary electrophoresis (CAPILLARYSTM; Sebia Electrophoresis). Immunofixation electrophoresis revealed no monoclonal immunoglobulin bands. QUESTIONS 1. What is unusual about the electrophoretic pattern? 2. What is responsible for this anomaly? The answers are on the next page. Fig. 1. Protein electrophoresis of the patient’s serum sample. Ref int, reference interval; Conc, concentration. Clinical Chemistry 59:2 448–455 (2013)