Skip to content

Immunoglobulin Lambda Light Chain in Serum (Free Light Chain)

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

This test measures the amount of free lambda light chains, which are small protein fragments produced by plasma cells. They are part of the immune system and can be elevated in certain 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
105983-1
Short code
IgM lambda Ser Ql IFE
Synonyms
IgM lambda Ser Ql IFE
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immunofixation
CPT
82784
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 This Test Measures

Free lambda light chains are produced by plasma cells, which are a type of white blood cell involved in fighting infections. Normally, these chains are bound to heavy chains in antibodies. When plasma cells become abnormal (as in multiple myeloma), they may produce excessive free light chains, which can appear in the bloodstream.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms like bone pain, frequent infections, or fatigue, or if you have a history of blood disorders. It’s also used to monitor treatment progress in certain cancers.

How the Test Works

A blood sample is drawn, and the serum is analyzed using an immunoassay method to detect free lambda light chains. The results help determine if levels are within expected ranges or elevated.

What the Results Mean

Results are typically reported as a ratio (e.g., free lambda/kappa light chains) rather than absolute values. High ratios may indicate plasma cell disorders, while normal ratios suggest no significant abnormality.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Lambda Light Chain

Frequently asked questions

What could cause elevated levels?
Elevated free lambda light chains are most commonly associated with multiple myeloma, a cancer of plasma cells. They can also occur in other conditions like monoclonal gammopathy of undetermined significance (MGUS) or certain autoimmune diseases.
What if my results are normal?
Normal results mean your free lambda light chains are within expected limits, but they don’t rule out all plasma cell disorders. Follow-up testing or monitoring may still be needed if you have symptoms or risk factors.
How often should I get this test?
Your doctor will determine the frequency based on your medical history, symptoms, and treatment plan. Regular monitoring may be required if you have a known plasma cell disorder.
  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