When a person is prescribed warfarin or Coumadin, regular blood tests are key to ensuring that their blood is clotting within a target range. Everyone reacts differently to anticoagulation treatment, due to differences in diet, stress, medications and other factors. That’s why it’s important to monitor your PT/INR regularly. A PT, or prothrombin time, is the time it takes for blood to clot, and the INR (International Normalized Ratio) is a standard for making results consistent no matter what type of PT test was used. You may see this referred to as PT monitoring, INR monitoring, or PT/INR, but it’s all the same thing. The goal of monitoring the effectiveness of your warfarin doses is to remain in the target range recommended by your doctor. If your PT/INR is higher than the target range, blood clots may not form quickly enough, and you may experience bruising or be at increased risk of bleeding. If it’s lower than the target range, you may still be at risk of excessive clotting, which can cause stroke or other serious problems.