Protein C Activity (Antithrombotic Function)
This test measures how well your protein C protein works to prevent blood clots. Protein C is an important part of your blood’s natural clotting system.
["Helps assess your risk for blood clots and monitor treatment for conditions like thrombosis."]
Key facts at a glance
- LOINC
- 55460-0
- Short code
- Deprecated Prot C Ag PPP
- Synonyms
- Deprecated Prot C Ag PPP
- Category
- chemistry
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have a history of blood clots, certain blood disorders, or are taking medications that affect clotting. It can also be used to check if your treatment for clotting problems is working properly.
What to Expect Before the Test
You’ll likely have a small needle inserted into your arm to draw blood. The process is quick and usually painless. If you’re on anticoagulant medications, your doctor may adjust your dose based on this test results.
How the Results Are Interpreted
Results are compared to a standard range to determine if your protein C levels are within normal limits or if they’re too low or too high. Low levels can increase your risk of clots, while very high levels may rarely cause bleeding issues.
Common Conditions Monitored
This test helps diagnose or manage conditions like protein C deficiency, disseminated intravascular coagulation (DIC), or evaluate responses to treatments for clotting disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Protein C plays a critical role in breaking down clots once they form. Low activity can lead to excessive clotting, while abnormal high levels may increase bleeding risk. Results guide treatment decisions for anticoagulant therapy or surgery planning.
Short name
Protein C Activity
Frequently asked questions
What does a low protein C activity level mean?
Can protein C levels change with age?
Is protein C testing the same as other blood clotting tests?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 16, 2026. · Read our editorial policy