Bence-Jones proteins are the abnormal proteins or immunoglobulin light chains found in the urine. A quantitative Bence-Jones protein test measures the specific level of these abnormal proteins in the urine sample. These proteins are made by plasma cells, a type of white blood cell and are not normally present in the urine. The presence of such proteins in the urine is associated with the malignancy of plasma cells. These are cancers of the lymphatic system. These proteins are considered as the first marker in detection of multiple myeloma, which is a type of blood cancer. This test is also known as Urine protein electrophoresis (UPEP) and immunoassay for free light chains
