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Serum or plasma free light chains (total)

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

This test measures the free light chains (the smaller protein parts) found in your blood, which can help diagnose conditions like multiple myeloma or other blood disorders.

Quick summary

["Free light chains in blood may signal hidden blood diseases or kidney problems."]

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

Key facts at a glance

LOINC
5359-5
Short code
GH Ab SerPl RIA-aCnc
Synonyms
GH Ab SerPl RIA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ria
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 Is This Test Done?

Your doctor may order this test to check for abnormal protein levels that could indicate conditions like multiple myeloma, lymphoma, or kidney disease. It’s often used alongside other tests, such as urine protein analysis, to monitor these conditions over time.

What Does the Test Measure?

The test measures the concentration of free light chains (κ or λ) in your blood, which are protein fragments produced by plasma cells. These fragments can accumulate abnormally in diseases like multiple myeloma or other hematologic malignancies.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma, where the light chains are measured using a specialized immunoassay technique.

What Are Common Results?

Results are reported as a concentration value (e.g., grams per liter). Elevated levels may suggest conditions like multiple myeloma, while normal or low levels may indicate no immediate concern, though further evaluation may still be needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Free light chains are produced by plasma cells and can be elevated in multiple myeloma, lymphoma, or other plasma cell dyscrasias. They may also reflect kidney function or other systemic diseases. Abnormal results often prompt additional testing, such as bone marrow biopsy or urine protein studies.

Short name

Total Free Light Chains

Frequently asked questions

What does an elevated free light chain test mean?
An elevated result may signal a blood disorder like multiple myeloma or another plasma cell disease. It could also indicate kidney problems or other conditions affecting protein metabolism. Your doctor will discuss next steps, such as further testing or monitoring.
How often should I get this test?
Frequency depends on your health condition and doctor’s recommendations. If you have a known blood disorder, this test may be done regularly (e.g., every few months) to track changes. If it’s a one-time screening, your doctor will guide you.
Can diet or medications affect this test?
Dietary changes or most over-the-counter medications typically do not affect free light chain levels. However, certain medications (e.g., chemotherapy, steroids) used in blood disorders may influence results. Always inform your doctor about all medications.
  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