Prothrombin Complex Activity (Prothrombin Time Ratio) - Plasma
This test measures how long it takes for your blood to clot, helping assess certain blood clotting factors and potential bleeding or clotting risks.
["Helps doctors check how well your blood clots and identify issues with clotting factors."]
Key facts at a glance
- LOINC
- 8616-5
- Short code
- PVCs nRate
- Synonyms
- PVCs nRate
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ekg
- 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 activity of blood clotting factors (prothrombin complex) by measuring the time it takes for blood to clot after an anticoagulant is added. This is often done to screen for or monitor conditions affecting clotting, such as liver disease or blood disorders.
Why It’s Done
Your doctor may order this test if you have symptoms like easy bruising, excessive bleeding, or if you’re taking blood thinners. It’s also used to monitor liver function, check for clotting disorders, or assess treatment effectiveness in conditions like vitamin K deficiency or liver disease.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. Plasma is separated from the blood cells and analyzed to measure the clotting time under controlled conditions.
Common Conditions Monitored
This test is commonly used to diagnose or monitor conditions like liver disease (which affects clotting factor production), vitamin K deficiency, blood clotting disorders (e.g., hemophilia), or to evaluate the effectiveness of anticoagulant medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated results may indicate liver disease, vitamin K deficiency, or certain blood disorders. Lower-than-expected results could suggest bleeding disorders or overuse of blood thinners. Results help guide treatment decisions, such as adjusting medication doses or identifying underlying health issues.
Short name
PT Ratio
Frequently asked questions
What does a high PT ratio mean?
What does a low PT ratio mean?
How often should I get this test?
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