The prothrombin time (PT) is a test used to help diagnose bleeding or clotting disorders. The international normalized ratio (INR) is a calculation based on results of a PT that is used to monitor treatment with the blood-thinning medication warfarin (Coumadin®). WARNING. BLEEDING RISK. COUMADIN can cause major or fatal bleeding [see WARNINGS AND PRECAUTIONS]. Perform regular monitoring of INR in all treated patients [see DOSAGE AND ADMINISTRATION]. Hi bigjhc2002, I have been on Coumadin for 8+ years and will be on it for life because of a blood clotting disorder called Factor 5 Leiden Disorder, I also get blood clots alot in both my lungs and my legs. Warfarin (Coumadin® / Jantoven®) 1. What is warfarin (Coumadin® / Jantoven®)? Warfarin is an anticoagulant. Sometimes warfarin is referred to as a “blood thinner,” however; 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. Generally when a person is on Coumadin, the Dr is looking for an INR range of 2-4 depending on what you are taking it for. That is a very general range. “In 2012, Advanced Cardiovascular Associates, PLC., partnered with Real-Time Diagnostics (RTD) for INR Management of our long-term Coumadin therapy patients. Usually while on Coumadin therapy, the INR should be between 2 and 3. Occasionally the range should be 2.5 to 3.5. Many things can affect the INR; antibiotics for one, and an increase or decrease in consumption of green, leafy vegetables. Low INR Levels. At a low INR Level, you're at risk for clots, and your blood is thicker. A low INR Level is relative to your target INR range. Vitamin K Levels in Common Foods Your quick guide to eating vegetables while taking Coumadin (warfarin).