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Serum or Plasma Free Light Chains (kappa and lambda)

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

This test measures the free light chains (kappa and lambda) found in your blood, which are small protein fragments produced by your immune system. These fragments can help diagnose conditions affecting your immune system, kidneys, or blood.

Quick summary

["Free light chains help identify immune disorders, kidney disease, or other conditions affecting protein balance in your body."]

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

Key facts at a glance

LOINC
45137-7
Short code
SIgA Fld-mCnc
Synonyms
SIgA Fld-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like fatigue, weight loss, or unexplained infections, or if you have a history of conditions such as multiple myeloma, lymphoma, or kidney disease. It can also be part of routine monitoring for certain treatments.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re taking blood pressure medication, let your provider know beforehand.

What the Results Mean

Abnormal levels of free light chains can indicate conditions like multiple myeloma (a cancer of plasma cells), kidney disease, or certain autoimmune disorders. High levels may also suggest overproduction of antibodies.

Common Conditions This Test Helps Diagnose

This test is often used to diagnose or monitor conditions like multiple myeloma, Waldenström macroglobulinemia, lymphoma, or kidney diseases such as light chain amyloidosis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chains

Frequently asked questions

What are the normal ranges for free light chains?
Normal ranges vary by lab and can depend on factors like age, sex, and overall health. Your results will be compared to your specific lab’s reference values.
How often should I get this test?
Your healthcare provider will determine the frequency based on your medical history, symptoms, and treatment plan. Regular follow-ups may be recommended if you have a condition like multiple myeloma.
Can diet or medications affect my free light chain levels?
Some medications, especially those affecting kidney function or immune responses, may influence results. Avoiding certain supplements or foods that could interfere with lab tests is always a good practice, but consult your provider first.
  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