Lab marker · Low

Low Protein C: what it means

A Protein C result below the normal range is considered low. Here is what a reduced Protein C can point to, and when it is worth discussing with a doctor.

Reference range: ~70–140% of normal activity; a vitamin-K-dependent natural anticoagulant — a LOW level (protein C deficiency) is a thrombophilia that raises the risk of abnormal venous clots

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What a low Protein C can mean

  • Inherited protein C deficiency — a genetic thrombophilia raising venous clot risk.
  • Warfarin — lowers protein C (so the test is done off warfarin).
  • Vitamin K deficiency — protein C is vitamin-K-dependent.
  • Liver disease — less protein C is made.
  • Active clotting or DIC — protein C is consumed.

When to discuss with a doctor

Protein C is a specialist test within a thrombophilia work-up, not a routine check. It is measured mainly after a blood clot that is unexplained, unusually severe, recurrent, in an unusual site or at a young age, or when there is a strong family history — to look for an inherited tendency to clot. A confirmed deficiency can influence how a clot is treated and prevented and prompts consideration for relatives. Timing matters: because warfarin, a recent clot and liver disease all lower protein C, the test and its interpretation are handled carefully by a haematologist so a temporary dip isn't mistaken for an inherited deficiency. Mediora.AI shows protein C alongside protein S, antithrombin and the clotting times so the thrombophilia pattern is read together; confirming and acting on a low result belongs with your doctor or haematologist.

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.