Prothrombin Time with Thrombin Addition (Activated Clotting Time Monitoring)
This test measures how long it takes for your blood to clot after a specific activator (thrombin) is added. It helps doctors monitor blood clotting function, especially in patients on blood thinners or undergoing procedures requiring careful blood control.
["Helps track how well your blood clotting is managed, particularly during treatment or surgery."]
Key facts at a glance
- LOINC
- 87178-0
- Short code
- Guided Ves Throm inf final W thr in cath
- Synonyms
- Guided Ves Throm inf final W thr in cath
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- imaging-modality
- 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
What This Test Measures
The test evaluates the time it takes for your blood to form a clot after thrombin is introduced. Thrombin is an enzyme that speeds up the clotting process. This measurement is critical for assessing the efficiency of your natural clotting factors and how they interact with added clotting proteins.
Why It’s Done
Your doctor may order this test if you’re on blood-thinning medications (like warfarin), preparing for surgery, or experiencing conditions that affect clotting, such as bleeding disorders or after a heart attack. It helps ensure your blood clots or stays fluid at the right balance for your treatment.
How It Works
A small sample of your blood is mixed with thrombin in a lab setting. The time it takes for a clot to form is recorded. This process mimics how thrombin naturally helps blood clot in your body, providing a snapshot of your clotting ability.
What to Expect Before the Test
No special preparation is needed unless your doctor specifies. You may have a small needle inserted into a vein (usually in your arm) to draw blood. The process is quick and typically painless, though you might feel a brief pinch.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is vital for monitoring anticoagulant therapy, diagnosing bleeding disorders, or assessing clotting dysfunction. Abnormal results may indicate whether your blood is clotting too quickly or too slowly, guiding treatment adjustments to prevent complications like bleeding or clots.
Short name
ACT Monitoring
Frequently asked questions
How long does it take to get results from this test?
Can I eat or drink before this test?
What does a prolonged or shortened clotting time mean?
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