Free Light Chains (Blood)
Does this test have other names?
Serum free light chain assay, Freelite
What is this test?
This test looks for signs of antibodies called immunoglobulins in your blood.
Immunoglobulins are made by white blood cells called plasma cells to help protect
you against infection and illness. Plasma, or myeloma, cells are found in your bone
marrow. Light chains, also called Bence Jones proteins, make up part of the structure
of immunoglobulins. Immunoglobulins are also made up of heavy chains.
The light chains attach themselves to the heavy chains and are then called bound light
chains. When you have more light chains than heavy chains, those extra light chains
are called "free" because they don't bind to the heavy chains. Instead, they are released
in the blood. The more free light chains in your blood, the more plasma cells you
have, which may mean there is a problem with the plasma cells.
This test is used to help diagnose a type of cancer called multiple myeloma. It may
also be used to diagnose other conditions affecting the cells in your bone marrow.
These include a usually benign condition called monoclonal gammopathy of undetermined
significance, or MGUS, and a serious disease called amyloidosis.
Why do I need this test?
You may need this test if your healthcare provider suspects a problem with your plasma
cells or multiple myeloma. You may not have signs and symptoms, but if you do, they
Pain in your bones
Increased protein on a blood test
A low red blood cell count (anemia)
High levels of calcium in the blood (hypercalcemia)
Inflammation in the blood vessels (vasculitis)
What other tests might I have along with this test?
Your healthcare provider may also order other tests, including:
Biopsy of your bone marrow
Electrophoresis tests of proteins in your blood
Electrophoresis tests of proteins in your urine
Free light chain test of your urine
Immunoglobulin test on your blood
Bone imaging tests
Other blood tests, including complete blood count, creatinine, and calcium
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Results are given in milligrams per liter (mg/L). The test measures the levels of
specific types of free light chains, known as kappa and lambda, and also the ratio
between the two. Normal test results for free light chains are:
3.3 to 19.4 mg/L kappa free light chains
5.71 to 26.3 mg/L lambda free light chains
0.26 to 1.65 ratio of kappa/lambda
If your results are higher or lower, it may mean you have a problem with your plasma
cells, such as multiple myeloma.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Other factors aren't likely to affect your results.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.