Serum or plasma free light chains (total)
This test measures the free light chains (the smaller protein pieces) produced by your immune system’s B cells. It helps assess conditions affecting plasma cells, such as multiple myeloma or other blood disorders.
["Free light chains can signal potential blood or immune system issues that may require further evaluation."]
Key facts at a glance
- LOINC
- 33090-2
- Short code
- GA from CRL.ASUM00
- Synonyms
- GA from CRL.ASUM00
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-estimated-from-crl-asum
- 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 order this test if you have symptoms like unexplained fatigue, frequent infections, or unexplained bone pain. It’s also used to monitor certain blood cancers, kidney disease, or autoimmune conditions.
What to Expect Before the Test
No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Abnormal results may indicate an imbalance in your immune system or kidney function. High levels could suggest conditions like multiple myeloma or other plasma cell disorders, while low levels might be seen in certain infections or immune deficiencies.
Common Conditions Monitored
This test is often used to diagnose or monitor multiple myeloma, lymphoma, or other blood disorders. It can also help track kidney function in patients with certain diseases.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free light chains are normally balanced in the body. When they become unregulated—such as in multiple myeloma or kidney disease—they can accumulate and cause harm. Elevated levels may trigger further testing for cancer or other systemic issues, while monitoring helps manage treatment effectiveness.
Short name
Total Free Light Chains
Frequently asked questions
What causes abnormal free light chain levels?
How are results interpreted?
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