Immunoglobulin G Free Light Chains (Serum)
This test measures the free light chains (the smaller protein parts) of immunoglobulin G (IgG), a type of antibody in your blood. Free light chains can be detected when the antibody fragments apart, which may occur in certain diseases.
["Understanding your free light chain levels helps identify conditions affecting antibody production or breakdown."]
Key facts at a glance
- LOINC
- 107198-4
- Short code
- IgH FR3 Spec
- Synonyms
- IgH FR3 Spec
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like fatigue, weight loss, or unexplained swelling, or if you have a history of conditions like multiple myeloma, lymphoma, or kidney disease. It may also be used to monitor treatment progress or check for abnormalities in antibody-related disorders.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re nervous, let your provider know—they can help make the process more comfortable.
What the Test Results Mean
Results show the concentration of free light chains in your blood. Elevated levels may suggest conditions like multiple myeloma or other antibody-related diseases, while normal or low levels typically indicate healthy antibody function. Your provider will discuss these results with you in detail.
Common Conditions Monitored
This test helps diagnose or track conditions such as plasma cell dyscrasias (abnormal antibody-producing cells), kidney diseases, or certain autoimmune disorders. It’s also used to check for hidden signs of cancer in blood-related tissues.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High levels of free light chains can indicate conditions like multiple myeloma, where abnormal plasma cells produce too many light chains. These chains can damage kidneys or cause other health issues. Your provider will work with you to determine the best next steps based on your full medical picture.
Short name
IgG Free Light Chains
Frequently asked questions
What causes free light chains to be detected in the blood?
How often should I get this test?
Can diet or lifestyle affect free light chain levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy