FLC Testing

A Free Light Chain (FLC) test is used to help detect, diagnose, and monitor plasma cell disorders (dyscrasias) such as multiple myeloma, primary amyloidosis, and related diseases or to monitor the effectiveness of treatment. You may have a blood sample drawn from a vein in your arm.


Normal Range:

For people with normal kidney function, the kappa/lambda ratio is around 0.26 to 1.65, and free light chains are present in the blood at low levels.


Abnormal Results:

  • Increased kappa free light chains and an increased kappa/lambda ratio mean there may be plasma cell disorders.
  • Increased lambda free light chains and a decreased kappa/lambda ratio also mean there may be plasma cell disorders.
  • In the context of MGUS or myeloma, significantly increased free light chains and a markedly abnormal kappa/lambda ratio mean there is an increased possibility of disease progression.
  • When monitoring a known plasma cell disorder, a decrease in the quantity of excess light chains and a more normal kappa/lambda ratio may indicate a response to treatment.


As the test has a poor specificity, the results of it are often evaluated in conjunction with those of a protein electrophoresis test.


Keywords: FLC; Free Light Chains; Kappa and Lambda Free Light Chains; Light Chains, Free; Free Kappa/Lambda Ratio; Quantitative Serum Free Light Chains with Ratio; Serum Free Light Chains; SFLC

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.