Skip to content

S100 Calcium-Binding Protein B (S100B) in Serum/Plasma

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

This test measures the level of S100B protein, a marker linked to brain cell damage and certain inflammatory conditions.

Quick summary

["S100B helps assess brain injury or inflammation but isn’t a standalone diagnosis tool."]

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

Key facts at a glance

LOINC
47274-6
Short code
S100 Ca binding protein B CSF-mCnc
Synonyms
S100 Ca binding protein B CSF-mCnc
Category
electrolyte
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What Is S100B Used For?

Doctors may order S100B testing to evaluate conditions like traumatic brain injury, subarachnoid hemorrhage, or certain neurological disorders. It can also help monitor inflammation or response to treatment in some cases.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in the arm. The sample is then processed to measure S100B levels using an immunoassay method, which detects the protein’s presence and concentration.

What Does a High or Low Level Mean?

Elevated S100B levels may indicate brain injury, inflammation, or other conditions affecting glial cells (supportive brain cells). Lower levels may suggest normal function or certain metabolic states, but interpretation depends on clinical context.

Common Conditions Monitored

S100B is often used alongside other tests to support diagnoses of traumatic brain injury, stroke, or conditions like multiple sclerosis. It’s not typically used alone for routine screening.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: S100B is a biomarker primarily used in specialized settings, such as trauma centers or neurology clinics, to assess brain pathology or monitor inflammatory responses. Its sensitivity varies by condition, so results are always evaluated with patient history and other diagnostic findings. Elevated levels may prompt further imaging or tests to pinpoint the cause.

Short name

S100B Protein

Frequently asked questions

Why might my doctor request this test?
Your doctor may order S100B testing if you’ve experienced a head injury, neurological symptoms, or conditions like inflammation or certain cancers that affect glial cells. It helps assess risk or monitor treatment progress.
What are the typical reference ranges?
Reference ranges can vary by lab and patient factors. Your doctor will discuss the results in relation to your specific health needs rather than a single numeric range.
Is this test painful or uncomfortable?
Drawing blood is a minor discomfort, but most people tolerate it quickly. Your healthcare provider will explain the process and any precautions afterward.
  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