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Serum or plasma free light chain kappa (κ) concentration

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

This test measures the amount of free kappa light chains, a small protein fragment produced by plasma cells, in your blood. It helps assess conditions affecting plasma cells, such as multiple myeloma or other cancers.

Quick summary

["This test helps diagnose and monitor certain blood-related disorders by tracking abnormal protein fragments in your bloodstream."]

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

Key facts at a glance

LOINC
83113-1
Short code
PSA Free SerPl IA-mCnc
Synonyms
PSA Free SerPl IA-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
4
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
84153
SNOMED
39392002
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, or kidney problems, or if they suspect conditions like multiple myeloma, lymphoma, or other plasma cell disorders. It can also be used to monitor treatment progress or check for recurrence.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re using blood thinners, inform your provider 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 less concerning but still warrant follow-up if symptoms persist.

Common Conditions Monitored

This test is often used to diagnose or monitor multiple myeloma, Waldenström macroglobulinemia, or other plasma cell dyscrasias. It may also help evaluate kidney function in patients with these conditions.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chain Kappa

Frequently asked questions

What causes elevated free light chain kappa levels?
Elevated levels are most commonly linked to multiple myeloma, where plasma cells overproduce abnormal proteins. Other causes may include certain lymphomas, autoimmune diseases, or kidney problems that filter proteins abnormally.
Can low levels of free light chain kappa be concerning?
Low levels alone are usually not concerning, but they may be part of a broader evaluation if you have symptoms like fatigue or kidney issues. Your provider will consider your full clinical picture.
How often should this test be repeated?
Frequency depends on your diagnosis and treatment plan. If you have multiple myeloma or another monitored condition, your provider may order this test every few months or as needed to track changes.
  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