What is this test?
Protein C is a natural anticoagulant protein that helps limit clot formation. Testing may measure activity or antigen and is used in selected assessments of inherited or acquired thrombophilia.
Why might it be ordered?
- After a clot when a specialist considers testing for protein C deficiency appropriate.
- For selected family investigations guided by a haematology or thrombosis specialist.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
The published schedule states Monday after 18:00; confirm current collection timing and whether fasting is requested. Acute thrombosis, liver disease, pregnancy and anticoagulants can affect the result. Never stop an anticoagulant without the prescribing clinician.
How should you understand the result?
A low value does not automatically prove an inherited deficiency. Abnormal results are often repeated when you are clinically stable and under specialist guidance.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.