Comparison between free light chains and immunofixation electrophoresis: one-year data from a tertiary hospital

Abstract Objectives Immunofixation electrophoresis (IFE) is a biochemical diagnostic method used in the diagnosis, treatment, and follow-up of monoclonal gammopathies. Paraproteinaemias involve overproduction of immunoglobulins, known as paraproteins or monoclonal proteins (M-proteins). M-protein can be detected as a sharp band on serum protein electrophoresis (SPE). Paraprotein types produced in monoclonal gammopathies can be detected by the IFE method. In our study, we aimed to retrospectively evaluate the types of paraproteinaemia detected by the IFE method in the laboratory and to compare our data with the literature. Methods A retrospective evaluation of the IFE results of a medical biochemistry laboratory of a tertiary care education and research hospital in Turkey in terms of the frequency and type of monoclonal gammopathy was performed in 2022. Serum free kappa/lambda (κ/λ) ratios and IFE results were compared. Results In our study, 1,169 serum IFE results were retrospectively analyzed, and paraprotein bands were detected in 116 different cases. The frequency of detected paraproteins was determined to be 10 %. A comparison between serum free κ/λ ratios and IFE results yielded 87 % concordance. Conclusions In our retrospective analysis, we obtained results similar to those reported in the literature in terms of serum immunofixation data, age, gender, and immunoglobulin types. We identified IgG-κ (20 %) as the most common paraprotein type. We believe that our study will contribute to the literature in terms of the frequency and variety of paraproteinemia. The κ/λ ratio is of limited use, since most abnormal IFE sera have normal free light chain (FLC) ratios.