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Serum or Plasma Free Light Chain Immunoglobulin (kappa or lambda) Ratio

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

This test measures the ratio of free light chains (kappa and lambda) in your blood, which can help diagnose conditions like multiple myeloma or other blood disorders.

Quick summary

["This test helps detect hidden blood diseases by checking for abnormal light chains in your bloodstream."]

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

Key facts at a glance

LOINC
47234-0
Short code
C trach Ag Fld Ql
Synonyms
C trach Ag Fld 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 Matters

Light chains are small protein fragments produced by plasma cells. When these cells become cancerous (as in multiple myeloma), they release too many light chains into the blood. Measuring their balance helps doctors identify abnormal production.

What to Expect Before the Test

No special preparation is needed. You’ll have a simple blood draw, usually from your arm. The test is quick and typically done in a lab setting.

How the Results Are Used

Results help doctors assess whether your blood contains abnormal amounts of light chains. High ratios may signal myeloma or other disorders affecting plasma cells.

Common Conditions Monitored

This test is often used alongside other blood tests to diagnose or monitor multiple myeloma, plasma cell leukemia, or other conditions where plasma cells behave abnormally.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chain Ratio

Frequently asked questions

What does a high or low light chain ratio mean?
A high ratio may indicate multiple myeloma or other plasma cell disorders, while low ratios are less common but could signal other blood-related conditions. Your doctor will interpret results in context with your full medical history and other tests.
Does this test require fasting?
No fasting is required for this blood test. It’s a simple draw, and results are typically ready within a few days.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition. For example, patients with multiple myeloma may get it regularly to monitor disease activity.
  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