The serum free light chain (FLC) ratio (kappa/lambda) is a blood test crucial for diagnosing and monitoring plasma cell disorders like multiple myeloma, comparing the body’s kappa to lambda light chains.
A normal range is typically 0.26 to 1.65, but abnormal ratios signal an imbalance, indicating higher risk of disease progression or worse outcomes, with laboratories adjusting ranges for kidney function.
Normal vs. Abnormal Normal: Around 0.26 to 1.65, meaning balanced production.
Abnormal: Below 0.26 or above 1.65, suggesting an excess of one type, often from a monoclonal gammopathy, like myeloma
An abnormal ratio means higher risk for conditions like MGUS or smoldering myeloma to progress to active myeloma.
Prognosis: Helps predict outcomes in myeloma and other related cancers, with increasingly abnormal ratios linked to worse survival.
Monitoring: Shows treatment effectiveness; decreasing abnormal ratios signals improvement.