Serum or plasma free light chains (total)
This test measures the levels of free light chains—small protein fragments produced by antibodies—found in your blood. It helps assess conditions affecting plasma cells, such as multiple myeloma or other blood disorders.
["Light chains in blood can signal underlying diseases affecting your immune system or bone marrow."]
Key facts at a glance
- LOINC
- 29343-1
- Short code
- RUBV IgG Fld-aCnc
- Synonyms
- RUBV IgG Fld-aCnc
- 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 Is Done
Your healthcare provider may order this test if you have symptoms like unexplained fatigue, frequent infections, or unexplained bone pain. It’s also used to monitor conditions like multiple myeloma, lymphoma, or other plasma cell disorders. Sometimes, it’s part of a broader evaluation for kidney disease or other immune-related illnesses.
What to Expect Before the Test
No special preparation is needed. You’ll typically have blood drawn from a vein in your arm. If you’re on blood thinners, let your provider know before the test to avoid unnecessary bleeding.
What the Results Mean
High levels of free light chains may indicate conditions like multiple myeloma, where abnormal plasma cells produce too many light chains. Low or normal levels usually don’t signal a problem unless part of a broader diagnostic workup. Your provider will interpret results in the context of your medical history and other tests.
Common Conditions Monitored
This test is often used to diagnose or track conditions such as multiple myeloma, Waldenström macroglobulinemia, or other plasma cell dyscrasias. It can also help evaluate kidney function or monitor treatment responses in patients with these disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal levels of free light chains can be a key diagnostic marker for certain blood cancers or immune system disorders. For example, elevated levels may suggest multiple myeloma, a cancer of plasma cells in the bone marrow. Monitoring these levels helps guide treatment decisions, such as chemotherapy or targeted therapies. Your provider may also use these results to assess kidney health, as light chains can sometimes affect kidney function over time.
Short name
Total Free Light Chains
Frequently asked questions
What causes abnormal free light chain levels?
How long does it take to get results?
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