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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 fragments released when antibodies break down) in your blood. It helps assess conditions affecting antibody production, such as multiple myeloma or other blood disorders.

Quick summary

["Light chains can signal serious blood or immune system conditions that may require further testing or treatment."]

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

Key facts at a glance

LOINC
63545-8
Short code
ENA SS-B Ab Fld Ql
Synonyms
ENA SS-B Ab Fld Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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, bone pain, or kidney problems. It’s also used to monitor treatment progress in certain blood cancers or autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Abnormal results may indicate conditions like multiple myeloma, lymphoma, or other immune-related disorders. Elevated levels could also suggest kidney disease or certain infections. Your provider will discuss findings with you based on your full medical picture.

Common Conditions Monitored

This test is often used to diagnose or track multiple myeloma, Waldenström macroglobulinemia, or other plasma cell dyscrasias. It may also help evaluate kidney function or monitor immune system disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chains

Frequently asked questions

What causes abnormal free light chain levels?
Abnormal levels are often linked to blood cancers (e.g., multiple myeloma), kidney disease, or autoimmune disorders. Rarely, infections or certain medications may also affect results.
How often will I need this test?
Frequency depends on your condition. If you have a blood disorder, your provider may order it every few months or as needed. For monitoring, it could be part of routine follow-ups.
Can diet or supplements affect this test?
Generally, no common foods or supplements interfere with free light chain tests. However, if you’re on medications (e.g., blood thinners), let your provider know to avoid potential interactions.
  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