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Protein C

Published: July 27, 2026Updated: August 25, 2026

Protein C is a vitamin K-dependent plasma glycoprotein that acts as an anticoagulant by inactivating factors Va and VIIIa in the coagulation cascade.

Quick summary

Protein C is a natural anticoagulant that helps regulate blood clotting.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
%
Clinical utility
diagnostic
Result kind
semi_quantitative
FDA-cleared
Roche Protein C, Siemens Protein C, Stago Protein C
interpretation: {"text":"May indicate a Protein C deficiency, increasing the risk of thrombosis and related clotting disorders.","label":"Low Protein C"}; {"text":"Generally not clinically significant, but may be seen in certain liver diseases or during anticoagulant therapy.","label":"High Protein C"}

Protein C is a crucial component of the natural anticoagulant system, playing a vital role in preventing excessive blood clotting. It functions by inactivating coagulation factors Va and VIIIa, thereby limiting the formation of thrombin and fibrin.

A deficiency in Protein C can lead to thrombophilia, a condition characterized by an increased risk of thrombosis (blood clots). This can manifest as deep vein thrombosis (DVT), pulmonary embolism (PE), or other clotting disorders.

Levels of Protein C are typically measured to diagnose deficiencies or to monitor patients on anticoagulant therapy. Normal levels range from 70% to 130%, and deviations can indicate underlying coagulation disorders.

Frequently asked questions

What causes low Protein C levels?
Low Protein C levels can be inherited or acquired, with causes including genetic mutations, liver disease, or vitamin K deficiency.
How is Protein C deficiency treated?
Treatment typically involves managing symptoms and preventing thrombosis through anticoagulant medications and lifestyle modifications.
  1. 1
    Protein C Deficiency - StatPearlsSource
  2. 2
    Role of Protein C in Coagulation - PMCSource

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 25, 2026. · Read our editorial policy