What types of proteins are commonly found in the urine of patients with multiple myeloma?

In patients with multiple myeloma, the presence of Bence Jones proteins in the urine is a hallmark finding. Bence Jones proteins are free light chains of immunoglobulin that result from the excessive production of monoclonal antibodies by malignant plasma cells. These proteins are small and can be filtered through the renal glomeruli, allowing them to appear in urine.

The detection of Bence Jones proteins is significant because it can help in the diagnosis of multiple myeloma and monitor the disease's progression or response to treatment. In laboratory tests, these proteins may be identified through urine protein electrophoresis, where they typically show a distinct band corresponding to the abnormal light chains.

In contrast, while albumin and other proteins can be present in urine for various reasons, they are not specific indicators of multiple myeloma. IgG antibodies are also found in the serum in large quantities in multiple myeloma, but they do not typically appear in the urine as Bence Jones proteins do. C-reactive protein serves as a nonspecific marker of inflammation and is not specific to the diagnosis of multiple myeloma or its renal manifestations. Thus, the predominance of Bence Jones proteins in the urine is a key indicator linked directly to the disease