Serum Free Light Chain Immunoassay (kappa and lambda)

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like unexplained fatigue, frequent infections, or unexplained bone pain. It’s also used to monitor conditions such as multiple myeloma, lymphoma, or other blood cancers. Sometimes, doctors check free light chains in people with kidney disease or other immune system disorders.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. The process is quick and usually painless. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results show the concentration of free kappa and lambda light chains in your blood. High levels may indicate conditions like multiple myeloma, where abnormal plasma cells produce too many light chains. Low levels alone are less common but can sometimes occur in certain immune disorders.

Common Conditions Linked to Abnormal Results

Elevated light chains are often linked to plasma cell disorders, such as multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS). They may also appear in other blood cancers like lymphoma or Waldenström macroglobulinemia. Kidney disease or certain infections can sometimes affect light chain levels too.