Immunoglobulin G (IgG) free light chains in serum/plasma
This test measures the amount of free light chains (the smaller protein fragments released when antibodies break down) produced by your immune system. These fragments can appear in higher-than-normal amounts in certain blood disorders.
["Free light chains may signal hidden immune system issues that aren’t detected by standard blood tests alone."]
Key facts at a glance
- LOINC
- 15181-1
- Short code
- IgA Fld-mCnc
- Synonyms
- IgA Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- 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 doctor may recommend this test if you have symptoms of conditions like multiple myeloma, lymphoma, or other blood cancers. It’s also used to monitor treatment progress or check for hidden abnormalities in people with chronic kidney disease or other immune-related illnesses.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. The test looks for free light chains in your serum or plasma, which are part of the larger antibody proteins your immune system produces.
What the Results Mean
Results are compared to a baseline or reference range for your condition. Elevated levels may indicate an overactive immune system breaking down antibodies, which can signal conditions like multiple myeloma or other cancers. Very low levels might suggest antibody deficiency or immune system dysfunction.
Common Conditions Linked to Abnormal Results
High levels of free light chains are often linked to multiple myeloma (a cancer of plasma cells), lymphoma, or other blood cancers. They can also appear in people with chronic kidney disease or certain autoimmune disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free light chains are a key diagnostic tool for detecting hidden blood cancers or immune system abnormalities. While standard blood tests may not show these fragments, this test can reveal subtle signs of disease progression or treatment response. It’s particularly useful in cases where symptoms are mild or non-specific.
Short name
IgG Free Light Chains
Frequently asked questions
What causes free light chains to be elevated?
How often should I get this test?
Can I do anything to lower my 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