Anomalous urinary proteins in patients with serum M-components.

Abnormal urinary proteins were investigated in 365 patients with serum M-components; 250 urines were available for study. All specimens were concentrated and processed by electrophoresis and immunoelectrophoresis. An overall frequency of Bence Jones proteinuria was found in 63%, whereas other M-components were detected in 18%. In patients with multiple myeloma, Bence Jones proteinuria occurred in 71%, while M-components in the form of whole molecules of immunoglobulins or as Fc and F'c fragments were observed in 20%. Bence Jones globulin was found in 60% of patients with IgG myeloma, 69% of those with IgA myeloma and 100% of patients with IgD myeloma and light chain disease. In regard to other diseases, Bence Jones proteinuria was found in 44% of patients with macroglobulinemia, in 60% of patients with nonplasmacytic neoplastic diseases and in 28% of patients with non-malignant conditions. Other M-components were detected in the urine of 13%, 14% and 6% respectively.The detection of abnormal urinary proteins in patients with M-components in the serum is an important diagnostic tool and may have prognostic significance.