Free Light Chains
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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. Light chains usually link up with other proteins called heavy chains.
Together, the light and heavy chains make immunoglobulins, also called antibodies. Antibodies are proteins that your immune system makes to fight germs such as viruses and bacteria. Light chains can be bound or free: When light chains link up with heavy chains, they are known as bound light chains.; Normally, your plasma cells will make a small amount of extra light chains that don't bind with heavy chains.
Instead, they are put into your bloodstream. These unlinked chains are known as free light chains.; There are two types of light chains: lambda and kappa light chains. You will usually have some of each in your blood.
A free light chains test measures the amount of lambda and kappa free light chains in your blood. If the amount of free light chains is higher or lower than normal, it may be a sign of a disorder of the plasma cells. These disorders include multiple myeloma, a cancer that begins in the plasma cells, and amyloidosis, a condition that occurs when abnormal proteins build up and collect in different organs and tissues.
Why this test is done
Your health care provider may order this test if you have symptoms of a plasma cell disorder. Depending on which plasma disorder you may have and which organs are affected, your symptoms may include:
- Bone pain, often in the back or ribs
- Fractures (broken bones)
- Weakness, numbness, or tingling in the arms or legs
- Fatigue
- Frequent infections and fevers
- Easy bruising or bleeding
- Trouble breathing
- Feeling very thirsty
- Frequent urination
- Tongue swelling
- Purple spots on the skin
How to prepare
You don't need any special preparations for a free light chains test.
Sample type
Blood
Other names for this test
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
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Educational content only. This entry describes what a test measures and how published reference ranges are defined. It is not a diagnosis, does not interpret your personal results, and is not a substitute for a qualified doctor.