Fibrinogen interference mimicking monoclonal band in serum protein electrophoresis of hemodialysis patient

Serum protein electrophoresis (SPE) is an important laboratory technique in the diagnosis of multiple myeloma. Analytical interference affects SPE as well as many other laboratory methods. Here, we have presented the fibrinogen interference that mimics the monoclonal band in the SPE in the sample sent in the gel biochemistry tube. A female patient presented to the emergency department with abdominal pain, nausea, and decreased urine output. In patients with high serum creatinine and blood urea nitrogen levels, a complete blood count has been found to be compatible with the presence of pancytopenia. Although an abnormal band similar to the M-spike protein was observed in the β/γ-region on the SPE evaluation, no monoclonal immunoglobulin was found in immunofixation electrophoresis. It was assured that the sample sent for SPE was collected in the correct tube (gel biochemistry tube). It was noted that the patient was receiving hemodialysis treatment while the sample was sent for SPE. It was considered that the specimen of the patient was contaminated with heparin. To test this theory, we added 1 ml of heparin to 5 ml of blood taken from a healthy subject in a gel biochemistry tube. Similarly, we observed that a band formed between the beta-gamma region in the SPE. Interferences are one of the most important causes of laboratory errors. Because they can have clinically important consequences such as misdiagnosis and treatment, laboratory specialists need to recognize these interferences and inform clinicians about them.