Lab marker · High

High S100 (S100B): what it means

A S100 (S100B) result above the normal range is considered high. Here is what a raised S100 (S100B) can point to, and when it is worth discussing with a doctor.

Reference range: ~<0.1 µg/L commonly used; a blood marker for advanced melanoma — used to monitor a known melanoma and watch for recurrence, not to screen for it

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What a high S100 (S100B) can mean

  • Advanced or spreading melanoma — a higher level tends to reflect a larger amount of melanoma.
  • A rising trend during follow-up — can signal progression or recurrence, prompting imaging.
  • Non-melanoma causes — S100 is also present in the brain and can rise after head injury or in some other conditions, so it is read in context.

When to discuss with a doctor

S100 is a specialist test, used within the care of a known melanoma — especially advanced or treated disease — rather than to screen for skin cancer. A suspicious or changing mole is assessed by looking at the skin and, if needed, removing it for examination, not by this blood test. Where S100 is used, its value is in the trend during follow-up: a rising level can be an early prompt to look for progression or recurrence with imaging, always interpreted with LDH, examination and scans by the oncology or dermatology team. A single mildly raised value has non-melanoma explanations and is not alarming on its own. Mediora.AI shows S100 alongside LDH so the pattern is visible; interpreting it belongs with your specialist team.

Conditions this can relate to

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.