Immunoglobulin Kappa Light Chain in Serum (Free Light Chains)

Why This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms like unexplained fatigue, frequent infections, or unexplained bone pain. It could also be part of a screening or monitoring plan for conditions like multiple myeloma, lymphoma, or other blood disorders. Sometimes, it’s used to check for overproduction of certain proteins in the blood.

What to Expect Before the Test

You’ll typically have a simple blood draw from a vein in your arm. No special preparation is needed, but let your provider know if you’re on blood-thinning medication or have a history of bleeding issues. The test usually takes a few minutes, and you can return to normal activities afterward.

What the Results Mean

Results are compared to a general reference range for healthy adults. High levels may suggest conditions like multiple myeloma, where plasma cells produce too many light chains. Low levels are less common but could indicate certain immune system disorders or medications that affect protein production.

Common Conditions Linked to Abnormal Results

Elevated free kappa light chains are often linked to multiple myeloma, a cancer of plasma cells, or other plasma cell dyscrasias. They can also appear in conditions like Waldenström macroglobulinemia or in response to certain medications or infections.