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
A free light chains test measures the level of free light chains in your blood. Light chains are proteins made by plasma cells, a type of white blood cell.
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
You don't need any special preparations for a free light chains test.
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
There is very little risk to having a blood test. 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 will show the amounts of lambda and kappa free light chains in your blood. It will also provide a comparison between the two, called a ratio.
- Results not normal: If your results were not normal, it may be a sign of a plasma cell disorder, such as: Multiple myeloma. MGUS (monoclonal gammopathy of unknown significance). This is a condition in which you have abnormal protein levels. Waldenstrom macroglobulinemia (WM), a cancer of the white blood cells. Limitation: A free light chains test is often ordered with other tests, including an immunofixation blood test, to help confirm or rule out a diagnosis. Next step: To understand the results of a free light chains test, your provider will consider your symptoms, medical history, and the results of other blood tests.
- Higher level with a kidney condition: You may also have a higher level of free light chains if you have a kidney condition. Limitation: In this case, a higher level may not mean that you have a plasma cell disorder. Next step: To understand the results of a free light chains test, your provider will consider your symptoms, medical history, and the results of other blood tests.
- 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
A free light chains test is often ordered with other tests, including an immunofixation blood test, to help 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?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.