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 ...