What urine finding is indicative of multiple myeloma?

The presence of Bence Jones proteinuria is a key urine finding indicative of multiple myeloma. In multiple myeloma, there is an overproduction of monoclonal immunoglobulins by malignant plasma cells. This results in the excretion of free light chains (kappa or lambda) of immunoglobulins in the urine. These free light chains, known as Bence Jones proteins, are unique to multiple myeloma and serve as a diagnostic marker for the disease. Detection of these proteins typically involves urine tests, such as immunofixation electrophoresis, which specifically identify the light chains.

The relevance of Bence Jones proteinuria lies in its ability to help confirm a diagnosis of multiple myeloma when combined with clinical findings and other laboratory results. It reflects the underlying pathology of the disease, where the production of abnormal proteins leads to various systemic effects and complications associated with multiple myeloma. Understanding this urine finding is crucial for clinicians when evaluating patients with possible multiple myeloma.