Bence–Jones proteins are free immunoglobulin light chains produced in excess by abnormal plasma cells.

They are excreted in urine and serve as a marker for plasma cell dyscrasias.

Clinical uses include:

Diagnosing multiple myeloma and Waldenström’s macroglobulinemia.

Monitoring disease progression and treatment response.

Differentiating causes of proteinuria (renal vs. hematological origin).

The test is performed on a 24-hour urine sample or spot urine, often alongside serum protein electrophoresis (SPEP) and immunofixation.

Analyte: Free immunoglobulin light chains (kappa or lambda) in urine.

Normal Result: Negative (no detectable Bence–Jones proteins).

Abnormal Findings:

Positive test: Indicates presence of monoclonal light chains, strongly suggestive of multiple myeloma or related disorders.

High levels: Associated with advanced disease and renal involvement.

Clinical Use:

Provides a specific marker for plasma cell malignancies.

Helps assess renal damage due to light chain deposition.

Guides diagnosis and monitoring in hematology and oncology practice.