Protein C Assay
- Sample Type
- Plasma
- Fasting
- No
- Unit
- % Activity
Function
Protein C is a vitamin K-dependent protein produced in the liver that serves as a natural anticoagulant. When activated (as Activated Protein C), it degrades Factors Va and VIIIa, which are essential components of the blood clotting cascade. The Protein C Assay measures the functional activity of this protein to ensure the body can properly regulate and prevent excessive blood clot formation.
Why it is Ordered
This test is primarily used in the workup of 'thrombophilia'—a tendency to develop blood clots. It is ordered for patients who have experienced unexplained Deep Vein Thrombosis (DVT), Pulmonary Embolism (PE), or clots at an unusually young age (under 50). It is also used to investigate 'Warfarin-induced skin necrosis,' a rare but serious complication of blood-thinning medication, and to screen family members of individuals with known Protein C deficiency.
Associated Conditions
- Congenital Protein C Deficiency: A hereditary risk factor for venous thromboembolism.
- Disseminated Intravascular Coagulation (DIC): Where Protein C is consumed rapidly.
- Liver Disease: Since the liver produces Protein C, levels drop in cirrhosis or hepatitis.
- Vitamin K Deficiency: Necessary for the synthesis of functional Protein C.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
Protein C levels are significantly affected by anticoagulant therapy. Testing while a patient is on Warfarin (Coumadin) will cause a false low result, as Warfarin inhibits the synthesis of Vitamin K-dependent proteins. Acute illness or recent clots can also 'consume' Protein C, leading to temporary low levels. Ideally, testing should be performed at least 2 weeks after stopping oral anticoagulants and when the patient is in a stable, non-acute state.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for Protein C Assay:
Official Sources
- Protein C Deficiency - StatPearls - NCBI Bookshelfncbi.nlm.nih.gov
- Clinical management of protein C deficiency - PubMedpubmed.ncbi.nlm.nih.gov
Research & Guidelines
- PubMed: Protein C Assay Clinical GuidelinesNCBI / PubMed
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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