Serum or Plasma Free Light Chain Immunoglobulin (Free Kappa and Lambda Light Chains)

Why This Test Is Done

Your doctor may order this test to check for conditions that affect how your bones or immune system work. For example, it can help identify multiple myeloma, a cancer of plasma cells, or other blood disorders like lymphoma or monoclonal gammopathy. It may also be used to monitor these conditions after treatment begins.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw, where a small needle is used to collect a sample from a vein in your arm. If you’re nervous, let your healthcare provider know so they can help make it more comfortable. If you’re on blood thinners, inform your doctor before the test.

What the Test Results Mean

Free light chains are usually balanced in healthy people, with equal amounts of kappa and lambda. If one type is too high, it may signal an issue like multiple myeloma or another blood disorder. Your doctor will compare your results to what’s expected for your age and health. They’ll also consider your medical history and other test results.

Common Conditions Monitored

High levels of free light chains are often linked to conditions such as multiple myeloma, where abnormal plasma cells produce too many light chains. They can also appear in other cancers (like lymphoma) or in people with kidney problems. Low levels alone are less common but may sometimes be seen in certain immune system disorders.