INR stands for International Normalized Ratio.
What does INR mean?
a standardized measure of how long blood takes to clot
INR stands for international normalized ratio, a standardized calculation based on the prothrombin time (PT) that allows clotting results to be compared across different laboratories. It is used mainly to monitor warfarin therapy. A normal INR is around 0.8 to 1.2, while people on warfarin usually have a target range of about 2.0 to 3.0, higher for certain conditions such as a mechanical heart valve. A high INR means slower clotting and a greater bleeding risk.
When is INR used?
INR is central to anticoagulation clinics and appears in medical, cardiology, and surgical notes for anyone taking warfarin.
Frequently asked questions
What does INR stand for?
INR stands for international normalized ratio, a standardized measure of clotting time.
What is a normal INR?
A normal INR is roughly 0.8 to 1.2. People on warfarin usually aim for about 2.0 to 3.0.
What does a high INR mean?
A high INR means the blood clots more slowly, which raises the risk of bleeding.
Why is INR used instead of PT alone?
INR standardizes PT results so they can be compared reliably across different laboratories.