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Understanding S100 and S100B Markers: What You Need to Know

Learn about S100 and its related markers, including typical ranges and when to consult a doctor.

Aug 22, 2026 2 min read

S100 proteins are a group of proteins involved in various cellular processes, such as cell growth and differentiation. S100B, a specific protein in this group, is often measured in the blood to monitor certain medical conditions. Understanding your S100B levels and related markers can help you and your healthcare provider manage your health effectively.

What is S100B and Why is it Important?

S100B is a protein found mainly in the brain and is involved in regulating several cellular functions. In the medical field, S100B is primarily used as a blood marker for advanced melanoma, a type of skin cancer. It helps in monitoring the progression of known melanoma cases and checking for recurrence after treatment. However, it is not used for screening melanoma in undiagnosed patients.

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Typical Levels of S100B

In adults, the typical range for S100B is 0 to 0.1 µg/L. This range is a guideline for what is considered normal in the general population. Levels below 0.1 µg/L are commonly used as a reference point. If you have a known case of melanoma, your doctor might use this marker to monitor your condition over time.

Factors That Influence S100B Levels

Several factors can influence S100B levels in the body. These include the presence of certain medical conditions like advanced melanoma. Other factors, such as brain injuries or neurological disorders, can also affect S100B levels. Therefore, it is crucial to interpret these results in the context of your overall health and medical history.

How to Interpret S100B Results

Interpreting S100B results involves considering the typical range and any factors that might affect your levels. If your S100B level is above 0.1 µg/L, it may indicate a need for further investigation, especially if you have a history of melanoma. Always discuss your results with your healthcare provider to understand what they mean for your specific situation.

Frequently asked questions

What does a high S100B level mean? A high S100B level, above 0.1 µg/L, could indicate the progression or recurrence of melanoma in patients with a known history of the disease. It is important to consult your healthcare provider for a comprehensive evaluation.

Can S100B levels be used to diagnose melanoma? No, S100B levels are not used to diagnose melanoma. They are used to monitor the condition in patients who have already been diagnosed.

Are there any conditions other than melanoma that affect S100B levels? Yes, conditions such as brain injuries or neurological disorders can also affect S100B levels. It is essential to consider your entire medical history when interpreting these results.

When to see a doctor

If your S100B levels are above 0.1 µg/L or if you have concerns about your melanoma management, it is important to consult your healthcare provider. They can help you understand your results in the context of your overall health and any other conditions you might have.

Remember, this article is for informational purposes only. Always discuss your lab results and health decisions with your clinician.

S100 (S100B): more on this topic

Test page What it measures, normal range, what moves it

Conditions where this test is key

Often checked together

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