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Free Light Chain Immunoglobulin (Serum or Plasma)

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

This test measures the free components of immunoglobulin light chains, which are small protein fragments produced by plasma cells. These fragments can be elevated in certain blood conditions.

Quick summary

["Elevated levels may signal multiple myeloma or other plasma cell disorders."]

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

Key facts at a glance

LOINC
104533-5
Short code
Immunoglobulin LC free Pnl SerPl
Synonyms
Immunoglobulin LC free Pnl SerPl
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 Is This Test Done?

Your healthcare provider may order this test to investigate symptoms like unexplained fatigue, bone pain, or kidney problems. It’s also used to monitor conditions like multiple myeloma, where abnormal plasma cells produce too many light chains.

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm. The blood is then separated into serum or plasma for testing.

What Does the Test Measure?

The test detects free light chains (κ or λ) that circulate in your blood. These chains are fragments of antibodies and can appear in higher amounts when plasma cells are abnormal.

What Are Common Findings?

Results may show elevated free light chains (kappa or lambda) if plasma cells are overproducing them, often linked to conditions like multiple myeloma or monoclonal gammopathy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated free light chains can indicate plasma cell disorders, such as multiple myeloma, where abnormal plasma cells produce excessive light chains. These fragments can also affect kidney function, leading to symptoms like swelling or fatigue. Low levels may suggest other immune-related conditions or normal variations.

Short name

Free Light Chain (FLC)

Frequently asked questions

What does a high or low free light chain result mean?
A high result may signal a plasma cell disorder like multiple myeloma, but further testing is needed to confirm. Your doctor will review your full clinical picture and other test results.
How often should I get this test?
Your doctor will determine the frequency based on your medical condition and treatment plan. Regular monitoring may be needed if you have a known plasma cell disorder.
Can lifestyle changes affect free light chain levels?
While diet and exercise generally don’t directly influence light chain levels, managing conditions like kidney disease or autoimmune disorders may indirectly affect test results.
  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