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Neurofilament light chain (NfL) in serum or plasma

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

This test measures levels of neurofilament light chain, a protein found in nerve cells. It helps assess nerve damage or disease progression in the brain or spinal cord.

Quick summary

["NFL blood tests may help track conditions affecting nerves over time."]

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

Key facts at a glance

LOINC
33418-5
Short code
Neuronal IgG Ser Ql
Synonyms
Neuronal IgG Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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

What Is Neurofilament Light Chain?

Neurofilament light chain (NFL) is a protein that makes up the cytoskeleton of nerve cells. When nerves are damaged, NFL can leak into the bloodstream. This test detects these elevated levels to identify nerve injury or disease.

Why Might You Need This Test?

Doctors may order this test to monitor conditions like multiple sclerosis, traumatic brain injury, or neurodegenerative diseases. It can also help evaluate nerve damage in other neurological disorders.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis using immunoassay techniques to measure NFL levels.

What Do Results Mean?

Higher than expected NFL levels may suggest nerve damage or disease activity. Lower levels might indicate less nerve injury. Your doctor will interpret results in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Neurofilament light chain blood tests are primarily used as a biomarker to monitor disease progression, response to treatment, or recovery in conditions affecting the nervous system. They are particularly valuable in chronic or progressive neurological diseases where traditional tests may not provide enough detail.

Short name

NFL Blood Test

Frequently asked questions

How long does it take to get my test results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing schedule. Your doctor will contact you once they are ready.
Can I eat or drink before this test?
You can eat and drink normally before this test, as it does not require fasting. However, always follow your healthcare provider’s specific instructions for your appointment.
Is there any risk or discomfort with this blood test?
The blood draw may cause mild discomfort or bruising at the site, but serious risks are rare. If you experience excessive bleeding or pain, inform your healthcare provider immediately.
  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