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Plasma Free Light Chain Immunofixation (Free Light Chains by Immunofixation)

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

This test measures the levels of free light chains (small protein fragments) in your blood, often used to diagnose and monitor conditions like multiple myeloma or other plasma cell disorders.

Quick summary

["Free light chains help identify unusual protein patterns that may signal hidden blood disorders."]

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

Key facts at a glance

LOINC
104153-2
Short code
LV EF US.3D.A3C+biplane
Synonyms
LV EF US.3D.A3C+biplane
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-d-a-c-calculated-by-biplane-method
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

What Is Free Light Chain Testing Used For?

Free light chains are produced by plasma cells, which are white blood cells that fight infections. When these cells become abnormal (e.g., in multiple myeloma), they may produce too many free light chains. This test helps detect these abnormal fragments in your bloodstream, aiding in diagnosing or monitoring conditions like plasma cell dyscrasias.

How Is This Test Performed?

A blood sample is drawn, and the plasma is separated for analysis. The test uses electrophoresis to separate and identify free light chains (κ [kappa] and λ [lambda]) and may include additional confirmation steps like immunofixation to detect monoclonal spikes.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like fatigue, bone pain, or kidney issues, or if tests like a complete blood count (CBC) or urine protein screening suggest an underlying plasma cell disorder.

What Do Results Mean?

Results show the presence and levels of free light chains. Elevated levels of one type (e.g., κ or λ) may indicate a monoclonal gammopathy, while abnormal ratios can help confirm conditions like multiple myeloma or other plasma cell diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chains Immunofixation

Frequently asked questions

Why was this test ordered?
Your healthcare provider may have suspected a plasma cell disorder (e.g., multiple myeloma) based on symptoms, lab findings, or other tests. Free light chains help confirm or monitor the disease by detecting abnormal protein fragments.
What does an abnormal result mean?
An abnormal result may indicate an excess of free light chains, which could signal a plasma cell disorder. Your doctor will interpret results in the context of your symptoms, other tests, and clinical picture to guide further care.
How often will I need this test?
Frequency depends on your diagnosis and treatment plan. If you have a plasma cell disorder, follow-up tests may be scheduled regularly to monitor disease progression or response to treatment.
  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