What is it used for?
A PT/INR test is most often used to:
See how well warfarin is working. Warfarin is a blood-thinning medicine that's used to treat and prevent dangerous blood clots. (Coumadin is a common brand name for warfarin.)
Find out the reason for abnormal blood clots
Find out the reason for unusual bleeding
Check clotting function before surgery
Check for liver problems
A PT/INR test is often done along with a partial thromboplastin time (PTT) test. A PTT test also checks for clotting problems.
