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Serum or Plasma Free Light Chain Immunoassay (Quantitative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the levels of free light chains (the smaller protein components of antibodies) in your blood, which can help diagnose conditions like multiple myeloma or other blood disorders.

Quick summary

["Free light chains help identify abnormal antibody production and related blood diseases."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
31165-4
Short code
MNBK Ur-mCnc
Synonyms
MNBK Ur-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
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, bone pain, or kidney problems. It’s also used to monitor treatment progress in certain blood cancers or immune disorders.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. It usually takes a few minutes, and you may feel a brief pinch.

What the Results Mean

High levels of free light chains can indicate conditions like multiple myeloma, lymphoma, or other immune system issues. Low or normal levels are typically within expected ranges for healthy individuals.

Common Conditions Monitored

This test helps diagnose and track conditions such as multiple myeloma, Waldenström macroglobulinemia, or other monoclonal gammopathies (abnormal antibody production).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Free light chains are fragments of antibodies produced by plasma cells. Elevated levels may signal plasma cell disorders, while abnormal ratios of kappa to lambda chains can confirm diagnoses like multiple myeloma.

Short name

Free Light Chains

Frequently asked questions

What causes abnormal free light chain levels?
Abnormal levels are often linked to plasma cell disorders (e.g., multiple myeloma), autoimmune diseases, or certain infections. Your provider will consider your symptoms and other test results for a full diagnosis.
How often should I get this test?
Frequency depends on your condition. If you have a known disorder like multiple myeloma, your provider may order this test regularly to monitor disease progression or treatment effectiveness.
Can diet or lifestyle affect free light chain levels?
Diet or lifestyle factors typically do not directly influence free light chain levels, as these are protein fragments measured in blood. Focus on managing your underlying condition with prescribed treatments.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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