Why it's done Most often, prothrombin time is monitored if you are taking the blood-thinning medicine warfarin. In this situation, the prothrombin time is shown as an international normalized ratio, also called INR.
Anticoagulant therapy with warfarin with a goal INR of 2 to 3 is effective in treating tissue valve thrombosis in most patients. Cardiac valve replacement and the risk of thrombosis are increasingly common in aging populations.
Blood tests, such as an INR, are needed to check for proper dosage and unwanted side effects. Be sure to keep all appointments. Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment and for at least 1 month after the last dose.