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Neurofilament Light Chain (NfL)

Published: July 27, 2026Updated: August 25, 2026

The Neurofilament Light Chain (NfL) biomarker measures the levels of a protein component of nerve fibers, which can indicate damage or degeneration of neurons.

Quick summary

NfL levels in pg/mL reflect neuronal damage and can aid in diagnosing neurological conditions.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
pg/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche NF-light, Quanterix NF-light, UMIN NF-light
interpretation: {"text":"0–100 pg/mL: Indicates no significant neuronal damage.","label":"Normal"}; {"text":">100 pg/mL: Suggests potential neuronal injury or degeneration.","label":"Elevated"}

Neurofilament Light Chain (NfL) is a structural protein found in the axons of neurons. Elevated levels of NfL in the blood or cerebrospinal fluid can indicate damage to nerve cells.

This biomarker is particularly useful in diagnosing and monitoring neurodegenerative diseases such as Alzheimer's, multiple sclerosis, and amyotrophic lateral sclerosis (ALS).

NfL levels above the reference range of 0–100 pg/mL may suggest ongoing neuronal injury, prompting further clinical evaluation.

Frequently asked questions

What conditions can cause elevated NfL levels?
Elevated NfL levels can be caused by neurodegenerative diseases, traumatic brain injury, and other conditions that result in neuronal damage.
How is the NfL test performed?
The NfL test is typically performed on a blood or cerebrospinal fluid sample using immunoassay techniques.
  1. 1
    Neurofilament light chain as a biomarker in neurological disordersSource
  2. 2
    Use of Neurofilament Light as a Biomarker in Neurological DisordersSource

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 25, 2026. · Read our editorial policy