Serum or Plasma Free Light Chain Immunoassay (kappa and lambda)
This test measures the free light chains (kappa and lambda) produced by plasma cells, which are part of your immune system. Abnormal levels may indicate conditions like multiple myeloma or other blood disorders.
["Free light chains help diagnose and monitor certain blood cancers and immune system disorders."]
Key facts at a glance
- LOINC
- 40751-0
- Short code
- EBV VCA IgM Ser Ql IF
- Synonyms
- EBV VCA IgM Ser Ql IF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- if
- 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 Is Done
Your healthcare provider may order this test to investigate symptoms such as unexplained fatigue, bone pain, or kidney problems. It can also be used to monitor treatment progress in patients with known conditions like multiple myeloma or lymphoma.
What to Expect Before the Test
No special preparation is needed. You may have a blood draw, and the sample is typically sent to a lab for analysis. If you’re on certain medications, let your provider know, as they may affect results.
How the Test Works
The test uses an immunoassay to detect free kappa and lambda light chains in your serum or plasma. These chains are fragments of heavy chains that are normally bound to antibodies but can become free in certain diseases.
Possible Results and Interpretation
Results are usually reported as separate values for kappa and lambda light chains. Elevated levels of one type (often kappa) may suggest a condition like multiple myeloma, while abnormal ratios can indicate other disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: Free light chains are typically balanced in healthy individuals. Unbalanced or elevated levels can signal conditions affecting plasma cells, such as multiple myeloma, lymphoma, or monoclonal gammopathy of undetermined significance (MGUS). Monitoring these levels helps guide treatment decisions.
Short name
Free Light Chains (FLC) Test
Frequently asked questions
What causes abnormal free light chain levels?
How are free light chain levels used in diagnosis?
Can diet or medications affect this test?
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