Serum or plasma free light chains (total)
This test measures the total amount of free light chains (the smaller protein pieces) found in your blood serum or plasma. These chains are fragments of antibodies and can be produced in excess when your immune system is overactive or malfunctioning.
["Understanding your free light chain levels helps identify immune system disorders or conditions affecting antibody production."]
Key facts at a glance
- LOINC
- 99926-8
- Short code
- RBC Fld Ql Auto
- Synonyms
- RBC Fld Ql Auto
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- automated
- CPT
- 85041
- SNOMED
- 900000000000003001
- 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 such as multiple myeloma, lymphoma, or other blood disorders. It may also be used to monitor treatment progress or check for complications in people with kidney disease or autoimmune disorders.
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood draw, where a small amount of blood is taken from a vein in your arm. If you’re having a urine test, you might be asked to collect a sample at home or in a lab.
What the Results Mean
Results are typically reported as a ratio of the two types of free light chains (kappa and lambda). High levels of one type (or an imbalance) may suggest certain blood disorders. Your doctor will interpret the results in the context of your overall health and medical history.
Common Conditions Monitored
This test is often used to diagnose or monitor conditions like multiple myeloma, lymphoma, or other plasma cell dyscrasias. It can also help detect kidney problems or other immune-related disorders that may affect antibody fragments in your blood.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Total Free Light Chains
Frequently asked questions
How is free light chain testing performed?
What are the normal ranges for free light chains?
Can free light chains be elevated due to other conditions besides blood disorders?
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 17, 2026. · Read our editorial policy