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Serum or Plasma Free Light Chain Kappa to Lambda Ratio (Free Light Chain Ratio)

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

This test measures the ratio of free kappa and lambda light chains in your blood, which helps assess conditions affecting plasma cells, such as multiple myeloma or other hematologic disorders.

Quick summary

["This ratio helps diagnose and monitor blood-related diseases by detecting imbalances in light chains."]

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

Key facts at a glance

LOINC
106599-4
Short code
N men DNA Fld Ql NAA+n-prb
Synonyms
N men DNA Fld Ql NAA+n-prb
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
non-probe-amp-tar
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, bone pain, frequent infections, or kidney problems. It may also be used to monitor conditions like multiple myeloma, lymphoma, or other blood disorders where abnormal light chains are involved.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

An abnormal ratio (either elevated or low) may indicate conditions like multiple myeloma, where one type of light chain is produced in excess. Normal results suggest balanced light chain production, but further testing may still be needed for diagnosis.

Common Conditions Monitored

This test is often used to diagnose or monitor multiple myeloma, Waldenström macroglobulinemia, lymphoma, or other plasma cell disorders. It can also help track treatment effectiveness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Light Chain Imbalance and Disease Progression

Short name

Free Light Chain Ratio

Frequently asked questions

What causes an abnormal light chain ratio?
Abnormal ratios are most commonly linked to plasma cell disorders, such as multiple myeloma (where kappa or lambda chains may dominate) or certain lymphomas. Chronic kidney disease can also affect light chain clearance, sometimes altering the ratio.
How often is this test repeated?
Frequency depends on your condition. If you have a plasma cell disorder, your provider may order this test every few months to monitor progression or response to treatment. Follow-up schedules are tailored to your specific diagnosis and treatment plan.
Can diet or medications affect this test?
Dietary changes or most over-the-counter medications typically do not affect light chain ratios. However, if you’re taking medications that impact kidney function (e.g., certain pain relievers or blood pressure drugs), inform your provider before testing.
  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