Doctor's Assessment Included
Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
Protein C (Activity)
Protein C Activity testing assesses a key natural anticoagulant. For older adults, acquired deficiency from liver disease or medications can compound age-related thrombotic risk.
What It Measures
This test measures the functional anticoagulant activity of Protein C, expressed as a percentage of normal.
Why It Matters
Protein C deficiency, whether inherited or acquired, is an important cause of thrombophilia. Early identification allows preventive measures during high-risk situations.
When to Test
Testing can be indicated for unexplained venous thrombosis, family history of Protein C deficiency, or as part of thrombophilia screening. Avoid testing on warfarin as it suppresses Protein C.
Symptoms
Low Levels
Low Protein C activity increases thrombosis risk. In adults, symptoms relate to thrombotic events (DVT, PE) rather than the deficiency itself.
High Levels
Elevated Protein C activity is generally not clinically significant and does not require intervention.
Lifestyle Tips
If Protein C deficiency is confirmed, reduce thrombosis risk factors, discuss anticoagulation for high-risk situations, and inform family members who may benefit from testing.
Frequently Asked Questions
How common is Protein C deficiency?
Inherited Protein C deficiency affects about 1 in 200-500 people. Most are heterozygous with moderately reduced levels.
Why avoid testing on warfarin?
Warfarin suppresses vitamin K-dependent proteins including Protein C, giving falsely low results.
Is Protein C related to Protein S?
Yes. Protein S is a cofactor for Protein C. Both are vitamin K-dependent natural anticoagulants.