Kappa Free Light Chain Test

What is a kappa free light chain test?

A kappa free light chain test is a blood test that measures the levels of a certain type of protein in your blood. Your plasma cells (a type of white blood cell that fights infections and illnesses) make light chains. Light chains usually link up with other proteins called heavy chains. Together, they make immunoglobulins (antibodies) and help your immune system work properly.

Providers call unlinked proteins in your blood “free light chains.” Your blood contains two types of free light chains: kappa and lambda light chains. It’s normal to have some of both. But some people have abnormally high or low levels of one or both types of free light chains in their blood. Free light chains outside of the normal range might mean you have a plasma cell disorder. The test is also used to monitor existing plasma cell disorders.

Other names for this test are a serum free light chain test or a free light chain assay test.

When is a kappa free light chain test needed?

A healthcare provider may order a kappa free light chain test if they think you have:

• Amyloidosis (protein disorder that causes organs to thicken).
• Lymphoproliferative disorder (too many lymph cells).
• Monoclonal gammopathy of undetermined significance or MGUS (abnormal proteins in the blood; it can progress to cancer).
• Multiple myeloma (plasma cell cancer, which may be kappa or lambda light chain myeloma).
• Solitary plasmacytoma (early-stage plasma cell cancer).
• Waldenström macroglobulinemia (a rare type of blood cancer).

Symptoms of these disorders may include:

• Anemia.
• Unusual bruising or bleeding.
• Bone lesions.
• Bone pain.
• Fatigue.
• Kidney problems or kidney disease.
• Numbness or tingling in arms and legs
• Skin rash or purple spots on your skin.
• Swollen tongue.
• Too much calcium in your blood (hypercalcemia).

How do I prepare for a kappa free light chain test?

You shouldn’t need to do anything to prepare for a kappa free light chain test. Your healthcare provider will let you know if there are any instructions you should follow before the test. In some cases, you may need to fast (no food or drink for eight hours) or stop taking certain medications before your blood test.

What happens during a kappa free light chain test?

A kappa free light chain test is a blood test. It only takes a few minutes. You might have the test at a lab, in your healthcare provider’s office or in a hospital.

During the test:

• A phlebotomist draws blood from a vein in your arm using a needle.
• They fill a collection tube with blood and then remove the needle from your arm.
• The phlebotomist puts a bandage on your arm (you can remove it in a few hours).

Are there any risks with a kappa free light chain test?

A kappa free light test doesn’t have any serious risks. During the test, you might feel a sting or some discomfort from the needle. Afterward, you may have a bruise, soreness or some light bleeding where the needle went into your arm. These symptoms usually go away within a few days.

When will I know the results of my kappa free light chain test?

Your healthcare provider will let you know when you can expect your results from a kappa free light chain test. It may take anywhere from a few days to a week to receive results.

What do kappa free light chain test results mean?

Normal results from a kappa free light chain test depend on the testing method and the lab’s established reference ranges.

The normal ranges for free light chains are generally:

• 3.3 to 19.4 milligrams per liter (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 outside of the normal ranges, you may have a plasma cell disorder. Kidney disease, chronic inflammation or an immune system disorder can also cause high levels of free light chains in your blood. However, in these cases, abnormal results don’t necessarily indicate a plasma cell disorder.

A note from Cleveland Clinic

A kappa free light chain test is a quick blood test that measures certain proteins in your blood. High levels of these proteins may mean you have a plasma cell disorder. A healthcare provider might order a kappa free light chain test if you have symptoms such as bone pain or fatigue.