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Serum or plasma free light chain kappa (immunoassay)

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

This test measures the amount of free kappa light chains, a small protein fragment produced when your immune system makes antibodies. These fragments can be found in your blood and are important for diagnosing certain conditions.

Quick summary

["Free kappa light chains help identify immune system disorders or kidney problems."]

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

Key facts at a glance

LOINC
43895-2
Short code
FLUBV Ag Nph Ql
Synonyms
FLUBV Ag Nph Ql
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 This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms like fatigue, weight loss, or swelling, or if you have a history of conditions such as multiple myeloma, lymphoma, or kidney disease. It can also be used to monitor treatment progress or check for abnormalities in your immune system.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the test if it involves drawing blood, but this is not always required for light chain tests. Always follow your provider’s instructions.

How the Test Works

A small sample of blood is taken from a vein in your arm. The blood is then sent to a lab where it is analyzed using an immunoassay method to detect free kappa light chains. This test helps measure their concentration in your serum or plasma.

Possible Results and Interpretation

Results can show elevated or low levels of free kappa light chains, which may indicate conditions like multiple myeloma, lymphoma, or kidney disease. Your healthcare provider will discuss the results with you and may recommend further testing if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Kappa Light Chain

Frequently asked questions

What does an abnormal result mean?
An elevated level of free kappa light chains can suggest an overactive immune system, such as in multiple myeloma or other plasma cell disorders. Low levels may be less common but could indicate certain immune deficiencies or other conditions affecting antibody production. Your provider will interpret results in the context of your overall health and symptoms.
Can this test be used to diagnose kidney disease?
While free kappa light chains can sometimes be elevated in kidney disease, they are not the primary test for diagnosing kidney problems. This test is more commonly used to monitor conditions affecting the immune system or plasma cells. Your provider may order additional tests if kidney function is suspected.
Is fasting required for this test?
No, fasting is generally not required for measuring free kappa light chains. However, always follow your healthcare provider’s instructions, as some tests may have specific preparation guidelines.
  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