Low S100 (S100B): what it means
A S100 (S100B) result below the normal range is considered low. Here is what a reduced 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
Understand your full resultWhat a low S100 (S100B) can mean
- A normal or low level is expected in early or well-controlled melanoma — and reassuring, but does not by itself prove the cancer is gone.
- A falling level during treatment — suggests the melanoma is responding.
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
Keep reading
One value is a snapshot. Upload the full test to see every marker explained together.
Upload your test - freeMediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.