Free Light Chains Understand the Test & Your Results (2024)

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  • What is a free light chains test?

    Light chains are proteins made by plasma cells, a type of white blood cell. Plasma cells also make immunoglobulins (antibodies). Immunoglobulins help protect the body against illness and infections. Immunoglobulins are formed when light chains link up with heavy chains, another type of protein. When light chains link up with heavy chains, they are known as bound light chains.

    Normally, plasma cells make a small amount of extra light chains that don't bind with heavy chains. They are instead released into the bloodstream. These unlinked chains are known as free light chains.

    There are two types of light chains: lambda and kappa light chains. A free light chains test measures the amount of lambda and kappa free light chains in the blood. If the amount of free light chains is higher or lower than normal, it can mean you have a disorder of the plasma cells. These include multiple myeloma , a cancer of plasma cells, and amyloidosis , a condition that causes a dangerous buildup of proteins in different organs and tissues.

    Other names: free kappa/lambda ratio, kappa/lambda quantitative free light, freelite, kappa and lambda free light chains, immunoglobulin free light chains

  • What is it used for?

    A free light chains test is used to help diagnose or monitor plasma cell disorders.

  • Why do I need a free light chains test?

    You may need this test if you have symptoms of a plasma cell disorder. Depending on which plasma disorder you may have and which organs are affected, your symptoms may include:

    • Bone pain
    • Fatigue
    • Numbness or tingling in arms and legs
    • Tongue swelling
    • Purple spots on the skin
  • What happens during a free light chains test?

    A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

  • Will I need to do anything to prepare for the test?

    You don't need any special preparations for a free light chains test.

  • Are there any risks to a free light chains test?

    There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

  • What do the results mean?

    Your results will show amounts for lambda and kappa free light chains. It will also provide a comparison between the two. If your results were not normal, it may mean you have a plasma cell disorder, such as:

    • Multiple myeloma
    • Amyloidosis
    • MGUS (monoclonal gammopathy of unknown significance). This is a condition in which you have abnormal protein levels. It often causes no problems or symptoms, but sometimes it develops into multiple myeloma.
    • Waldenstrom macroglobulinemia (WM), a cancer of the white blood cells. It's a type of non-Hodgkin lymphoma .

    Learn more about laboratory tests, reference ranges, and understanding results .

  • Is there anything else I need to know about a free light chains test?

    A free light chains test is often ordered with other tests, including an immunofixation blood test , to help confirm or rule out a diagnosis.

  • References
    1. American Cancer Society [Internet]. Atlanta: American Cancer Society Inc.; c2019. Tests to Find Multiple Myeloma; [updated 2018 Feb 28; cited 2019 Dec 21]; [about 4 screens]. Available from:
    2. American Cancer Society [Internet]. Atlanta: American Cancer Society Inc.; c2019. What is Waldenstrom Macroglobulinemia?; [updated 2018 Jul 29; cited 2019 Dec 21]; [about 3 screens]. Available from:
    3. American Society of Hematology [Internet]. Washington D.C.: American Society of Hematology; c2019. Myeloma; [cited 2019 Dec 21]; [about 3 screens]. Available from:
    4. International Myeloma Foundation [Internet]. North Hollywood (CA): International Myeloma Foundation; Understanding Freelite and Hevylite Tests; [cited 2019 Dec 21]; [about 3 screens]. Available from:
    5. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Serum Free Light Chains; [updated 2019 Oct 24; cited 2019 Dec 21]; [about 2 screens]. Available from:
    6. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. Monoclonal gammopathy of undetermined significance (MGUS): Symptoms and causes; 2019 May 21; [cited 2019 Dec 21]; [about 3 screens]. Available from:
    7. Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2021. Test ID: FLCS : Immunoglobulin Free Light Chains, Serum : Clinical and Interpretative; [cited 2021 Aug 10]; [about 4 screens]. Available from:
    8. National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (PDQ®)–Patient Version; [updated 2019 Nov 8; cited 2019 Dec 21]; [about 3 screens]. Available from:
    9. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [cited 2019 Dec 21]; [about 3 screens]. Available from:
    10. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Free Light Chains (Blood); [cited 2019 Dec 21]; [about 2 screens]. Available from:
Free Light Chains Understand the Test & Your Results (2024)


How to interpret light chain results? ›

If the amount of free light chains is higher or lower than normal, it may be a sign of a disorder of the plasma cells. These disorders include multiple myeloma, a cancer that begins in the plasma cells, and amyloidosis, a condition that occurs when abnormal proteins build up and collect in different organs and tissues.

What does it mean when free Kappa light chain is high? ›

The more free light chains in your blood, the more plasma cells you have. This 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.

Is it normal to have light chains in urine? ›

Light-chain proteins may manifest in the urine because of the following: Asymptomatic light-chain proteinuria. Proximal tubular dysfunction (ie, Fanconi syndrome) Chronic kidney disease or acute kidney injury.

What is the normal range for Kappa free light chains? ›

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.

What autoimmune disease causes free light chains? ›

Increased free light chain concentrations have been described in a variety of inflammatory and autoimmune diseases including systemic lupus erythematosus (SLE) [13,14], rheumatoid arthritis, Sjögren's syndrome [15], atopic dermatitis [16], asthma [17], rhinitis [18,19], food allergy [20], idiopathic pulmonary fibrosis, ...

What is the life expectancy of someone with light chain disease? ›

Median survival for patients with light-chain deposition disease (LCDD) is about 4 years. The largest series published so far has reported after a median follow-up of 27 months; 57% of patients developed uremia and 59% of patients died.

What causes free light chains to increase? ›

Excess light chain production may be seen with any plasma cell disorder, such as multiple myeloma, MGUS (monoclonal gammopathy of unknown significance – a condition that may progress to multiple myeloma), and monoclonal light chain (primary) amyloidosis (see Common questions above).

What are the light chains in urine for myeloma? ›

Urine test (Light chain / Bence Jones protein) Your doctor is likely to ask you for a urine sample. This is to check for abnormal antibodies (paraproteins) made by myeloma cells. One part of the paraprotein is the light chain or Bence Jones protein, which the body gets rid of in the urine.

Is light chain a terminal disease? ›

Amyloid light chain amyloidosis, shortened to AL amyloidosis, is a rare and often fatal disease.

Why would a doctor order a free light chain test? ›

Serum free light chain (SFLC) testing is ordered to help detect, diagnose, and monitor plasma cell disorders (dyscrasias), including multiple myeloma, primary amyloidosis, and related diseases or to monitor the effectiveness of treatment. Light chains are proteins produced by plasma cells.

Can free light chains fluctuate? ›

It is normal for there to be small fluctuations in the uninvolved light chain concentration over time, which have no clinical significance at all.

What is usually the first symptom of multiple myeloma? ›

Multiple myeloma causes many symptoms, but bone pain often is the first symptom people notice. Other symptoms include: Weakness in your arms and legs and/or a sensation of numbness in your arms and legs.

What kappa-lambda ratio indicates myeloma? ›

The reference standard to classify as multiple myeloma required meeting any of the following (1) kappa/lambda ratio ≤1/16 or ≥16, (2) abnormal plasma cell morphology, and (3) monoclonal immunoglobulin.

What if kappa and lambda are both high? ›

Some people may have high kappa and lambda light chains but a normal ratio. These people may have a diseases associated with general stimulation of the immune system.

What is a high kappa-lambda ratio for lymphoma? ›

The normal kappa to lambda ratio is considered to be 0.37-0.96. A ratio of higher than 0.96 indicates a high amount of kappa light chain and a ratio of lower than 0.37 indicates a higher than normal amount of lambda being produced.

What is the serum light chain in multiple myeloma? ›

Light chain myeloma is a subtype of multiple myeloma. Cancerous plasma cells, or myeloma cells, produce immunoglobulins. These immunoglobulins consist of heavy and light chain proteins. A person has light chain myeloma if the immunoglobulins from myeloma cells only contain light chain proteins.

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