The Prothrombin Time (PT) test measures how long it takes your blood to clot.
It’s used to check for bleeding or clotting disorders and to monitor patients on blood-thinning medicines like warfarin
Doctors may recommend a PT test to:
Diagnose bleeding disorders.
Check liver function (liver makes clotting proteins).
Monitor anticoagulant therapy (e.g., warfarin).
Investigate unexplained bleeding or bruising.
Check before surgery to ensure normal clotting.
Prothrombin time in seconds (normal: ~11–13.5 sec).
INR (International Normalized Ratio) – a standardized value for comparing results between labs.
Normal INR: ~0.8 – 1.1
On warfarin: Target INR usually 2.0 – 3.0 (varies as per condition).
A blood sample is taken from a vein in your arm.
In the lab, chemicals are added to trigger clotting, and the time taken is measured.
No fasting required.
If you are taking blood thinners or any medicine, inform your doctor — it can affect results.
