Free Light Chains
A free light chains test measures specific proteins in your blood to help diagnose and monitor disorders of the plasma cells.
What is a free light chains test?
This test measures the level of free light chains in your blood. Light chains are proteins produced by plasma cells, a type of white blood cell. Normally, these proteins link with heavy chains to form immunoglobulins (antibodies) that fight infection. A small amount of unlinked "free" light chains is normal, but abnormal levels can indicate plasma cell disorders.
There are two types of light chains: lambda and kappa. The test measures both and compares their ratio.
What is it used for?
The test is used to diagnose or monitor the treatment of plasma cell disorders, including multiple myeloma (a cancer of the plasma cells) and amyloidosis (a condition where abnormal proteins build up in organs).
Why do I need a free light chains test?
Your provider may order this test if you exhibit symptoms of a plasma cell disorder, which may include:
- Bone pain, particularly in the back or ribs
- Fractures
- Weakness, numbness, or tingling in the limbs
- Fatigue
- Frequent infections or fevers
- Easy bruising or bleeding
- Trouble breathing
- Excessive thirst or frequent urination
- Tongue swelling or purple spots on the skin
What happens during a free light chains test?
A health care professional will collect a blood sample from a vein in your arm using a small needle. The procedure usually takes less than five minutes and requires no special preparation.
What do the results mean?
The results provide the levels of lambda and kappa light chains and their ratio. Abnormal results may indicate:
- Multiple myeloma
- Amyloidosis
- MGUS (monoclonal gammopathy of unknown significance)
- Waldenstrom macroglobulinemia (a type of non-Hodgkin lymphoma)
Higher levels of free light chains may also be caused by kidney conditions rather than a plasma cell disorder. Your provider will evaluate these results alongside your medical history and other blood tests.