People who are taking certain anticoagulant medications, such as warfarin (Coumadin®, Jantoven®), will need to have an international normalized ratio (INR) test to make sure their dosage is safe and effective. This test measures how long it takes the blood to clot.
If you have a low INR, it means that it does not take long for your blood to clot. INR values that are too low indicate that a person may have an increased risk of developing a blood clot or stroke.
(Click INR for a closer look at what may happen if your value is too low. This eMedTV article also explains the potentially serious complications that may occur if your INR is too high.)