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Immunoglobulin Kappa Light Chain in Serum (Free Light Chains)

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

This test measures the amount of free kappa light chains, a component of antibodies, in your blood serum. It helps identify conditions affecting antibody production or breakdown.

Quick summary

["This test may help diagnose certain blood disorders or kidney issues linked to abnormal antibody fragments."]

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

Key facts at a glance

LOINC
107197-6
Short code
IgK gene Tube A Spec
Synonyms
IgK gene Tube A Spec
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
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 recommend this test if you have symptoms like fatigue, weight loss, or unexplained swelling, or if they suspect conditions such as multiple myeloma, lymphoma, or kidney disease. It can also be part of monitoring for these conditions or other immune-related disorders.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm 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 kappa light chains can indicate conditions like multiple myeloma, where abnormal antibody-producing cells release these fragments. Low or normal levels are less concerning but may still warrant further evaluation if symptoms persist.

Common Conditions Monitored

This test is often used alongside other blood tests to diagnose or track conditions such as plasma cell disorders, kidney disease, or certain autoimmune diseases. It helps assess whether your treatment is working or if additional interventions are needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated free kappa light chains are a hallmark of monoclonal gammopathy, including multiple myeloma, where a single type of antibody (immunoglobulin) becomes overproduced. These fragments can also indicate kidney damage if they accumulate in the bloodstream. Monitoring these levels helps guide treatment decisions and manage complications early.

Short name

Free Kappa Light Chains

Frequently asked questions

What causes abnormal free kappa light chain levels?
Abnormal levels are most commonly linked to conditions like multiple myeloma, where cancerous plasma cells produce excessive light chains. Rarely, they may also appear in other blood cancers (e.g., lymphoma), infections, or kidney diseases. Your provider will consider your full medical history and other test results to determine the cause.
How often will I need this test?
Frequency depends on your diagnosis and treatment plan. If you have a known condition like multiple myeloma, your provider may order this test regularly to monitor disease progression or response to treatment. If it’s part of routine screening, it may be less frequent.
Can lifestyle changes affect this test result?
While diet and exercise generally don’t directly impact free kappa light chains, managing conditions like kidney disease or autoimmune disorders through lifestyle changes may indirectly influence test results. Always discuss any changes with your provider before interpreting results.
  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