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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 (kappa and lambda) in your blood, which are protein fragments produced by plasma cells. These fragments can help diagnose conditions like multiple myeloma, lymphoma, or other blood disorders.

Quick summary

["Light chain tests help identify abnormal protein production in your immune system."]

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

Key facts at a glance

LOINC
68368-0
Short code
WBC # Dial fld Auto
Synonyms
WBC # Dial fld Auto
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.5
Ref high
11
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
automated-count
CPT
85004
SNOMED
900000000000003002
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 Is Done

Your healthcare provider may order this test if you have symptoms like unexplained fatigue, frequent infections, bone pain, or kidney problems. It may also be used to monitor conditions like multiple myeloma, lymphoma, or other blood cancers, or to check for kidney disease caused by abnormal proteins.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm or vein to draw blood. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

High levels of free light chains may indicate conditions like multiple myeloma, where plasma cells produce too many abnormal proteins. Low or normal levels are usually not concerning unless your provider has a specific reason to suspect a problem.

Common Conditions Monitored

This test is often used to diagnose or monitor multiple myeloma, lymphoma, or other blood disorders. It can also help assess kidney function if abnormal proteins are suspected.

Reference range

Adult: 4.5-11.0 x 10^9/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chain Test

Frequently asked questions

What causes abnormal light chain levels?
Abnormal light chain levels are most commonly linked to conditions like multiple myeloma, where plasma cells produce too many abnormal proteins. They can also appear in other blood cancers, infections, or kidney diseases.
How often should I get this test?
Your provider will determine how often you need this test based on your health condition, treatment plan, and symptoms. Follow-up tests may be scheduled every few months or as needed.
Can diet or medications affect light chain test results?
Dietary changes or most over-the-counter medications typically do not affect light chain levels. However, if you’re on medications that affect kidney function or blood protein production, let your provider know.
  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