© American Society for Clinical Pathology Immunopathology / M PROTEINS IN HYPOGAMMAGLOBULINEMIC PATIENTS Detection by Immunofixation of M Proteins in Hypogammaglobulinemic Patients With Normal Serum Protein Electrophoresis Results

A b s t r a c t Serum protein electrophoresis (SPE) demonstrates a monoclonal protein as an M spike in the majority of patients with monoclonal gammopathies. However, in patients with an apparently normal SPE pattern or hypogammaglobulinemia, immunofixation electrophoresis (IFE) can reveal an M protein. We undertook this study to determine the yield of reflex IFE testing in patients with hypogammaglobulinemia and to identify any laboratory or biochemical parameters that would predict a positive IFE result. We evaluated 380 patients with hypogammaglobulinemia and a normal SPE pattern. Of 380, 37 (9.7%) had a positive IFE result in serum, urine, or both. Of the other laboratory values evaluated, a high α2-globulin level with a