Free Light Chains
Reviewed
Also called: free kappa/lambda ratio, kappa/lambda quantitative free light, freelite, kappa and lambda free light chains, immunoglobulin free light chains, free light chain assay test
Measures the level of free light chains in the blood, used to diagnose or monitor plasma cell disorders such as multiple myeloma and amyloidosis.
Specimen: Blood
Why this test may be ordered
- To help diagnose plasma cell disorders such as multiple myeloma, amyloidosis, MGUS, Waldenstrom macroglobulinemia
- To monitor how well treatment of plasma cell disorders is working
Preparation and collection
No special preparation needed.
A blood sample is taken from a vein in your arm, typically taking less than five minutes.
Very little risk; you may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Your results include the levels of lambda and kappa free light chains and their ratio (kappa/lambda ratio). Your healthcare provider will interpret these values along with your symptoms and medical history.
- Normal ratio and levels: Your free light chain levels and kappa/lambda ratio are within normal range, making a plasma cell disorder less likely. Limitation: A normal result does not completely rule out all plasma cell disorders, and clinical correlation is needed. Next step: Your provider will evaluate your symptoms and may recommend other tests if symptoms persist.
- Abnormal kappa/lambda ratio: An abnormal free light chain ratio may indicate a plasma cell disorder such as multiple myeloma, amyloidosis, MGUS, or Waldenstrom macroglobulinemia. Limitation: This result alone does not confirm a diagnosis; kidney disease can also affect free light chain levels and ratio. Next step: Your provider will likely order additional tests such as immunofixation blood test, serum protein electrophoresis, urine tests, and imaging to confirm a diagnosis.
- Elevated free light chains with normal ratio: Elevated free light chains but normal ratio may be due to kidney conditions or less likely a plasma cell disorder. Limitation: Kidney disease is a common cause of elevated free light chains; further evaluation is needed. Next step: Your provider may check kidney function and other tests to differentiate between renal cause and plasma cell disorder.
- Elevated free light chains can occur due to kidney conditions and not necessarily plasma cell disorder
- Results must be interpreted along with other tests and medical history
- Abnormal results do not confirm a specific diagnosis without further evaluation
What to do next
Your healthcare provider will consider your symptoms, medical history, and may order additional tests such as immunofixation blood test or other tests to confirm or rule out a diagnosis.
- What symptoms might indicate I need this test?
- What does the free light chains ratio tell my doctor?
- Could my kidney condition affect my test results?
- What other tests might I need along with this one?
- How is this test used in monitoring treatment?