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Plasma or Serum Free Light Chain Kappa (Immunoglobulin Light Chain Kappa)

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

This test measures the amount of free kappa light chains in your blood, which are small protein fragments produced by plasma cells. These fragments can help diagnose conditions like multiple myeloma or other blood disorders.

Quick summary

["Free kappa light chains help detect abnormal protein production in blood disorders."]

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

Key facts at a glance

LOINC
20499-0
Short code
PG MFr Amn
Synonyms
PG MFr Amn
Category
glucose
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test to investigate symptoms such as unexplained fatigue, frequent infections, bone pain, or kidney problems. It can also be used to monitor certain blood cancers, like multiple myeloma, or other conditions affecting plasma cells.

What to Expect Before the Test

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

What the Test Results Mean

High levels of free kappa 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 part of a broader evaluation.

Common Conditions Monitored

This test is often used alongside other blood tests to diagnose or track conditions such as multiple myeloma, Waldenström macroglobulinemia, or other monoclonal gammopathies (disorders of plasma cells).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Kappa Light Chain

Frequently asked questions

What causes elevated free kappa light chains?
Elevated levels are most commonly linked to plasma cell disorders, such as multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS). Other rare conditions, like certain lymphomas or infections, may also cause changes.
Can this test be done on urine instead of blood?
No, this test specifically measures free kappa light chains in plasma or serum, not urine. Urine tests often measure total light chains or other markers.
How often should this test be repeated?
Your provider will determine the frequency based on your diagnosis and symptoms. Regular monitoring may be needed 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