High INR Levels. At a high INR Level, you're at risk for internal bleeding, and your blood is thinner. A high INR Level is relative to your target INR range. CoaguChek XS PT Test Strips are used with Roche INR Test Meters to monitor patient response to the blood thinner warfarin. Why It Is Done. Prothrombin time (PT) is measured to: Find a cause for abnormal bleeding or bruising. Check the effects of warfarin (Coumadin). You will have the test regularly to make sure you are taking the right dose. Terrific Care, LLC. / Medex Supply Recalls CoaguChek XS PT Test Strips Used to Monitor Blood Thinner Warfarin Due to Inaccurate Test Results If your PT/INR test result is too low, it means that your dose of warfarin may not be enough to protect your blood from clotting. Your warfarin dose needs to be increased. The international normalised ratio (INR) is a laboratory measurement used to determine the effects of oral anticoagulants such as warfarin on the body's blood clotting. Understanding the PT-INR Test. Marie B. Walker January, 2004 If you have ever undergone oral anticoagulation therapy, you have most likely heard of the PT-INR test, but you may not understand what it is and/or what it means. The U.S. Food and Drug Administration (FDA) has published new information on the agency’s website for people who take warfarin (a blood thinner) and use portable, battery-operated INR test meters to monitor their therapy. Patient Self Testing Marie Bussey Henry I. Bussey, Pharm.D. Updated August, 2012 Originally Posted May 2004 In the Understanding the PT-INR Test section of ClotCare, I mention that the traditional way to run a PT-INR test is to have your blood drawn and sent to a lab, where the test is conducted. A prothrombin time (PT) is a test used to help detect and diagnose a bleeding disorder or excessive clotting disorder; the international normalized ratio (INR) is calculated from a PT result and is used to monitor how well the blood-thinning medication (anticoagulant) warfarin (Coumadin®) is working to prevent blood clots.