A healthcare provider may prescribe a blood-thinning medication, such as warfarin (Coumadin®, Jantoven®), to help prevent a blood clot or stroke. However, it is important to monitor your blood levels of these medications to reduce your risk for developing potentially serious complications.
To help ensure your dosage is at a safe and effective amount, you will routinely have a blood test to measure your international normalized ratio (INR). This value is a measurement of how long it takes for your blood to clot. A healthy person who is not taking a blood thinner typically has an INR of 1. People taking blood thinners should have an INR value between 2 and 3.
If your value of INR is too high, it may increase your risk for uncontrollable bleeding; an INR that is too low may put you at risk for a blood clot or stroke.
(For more details on how these values are measured, click INR. This Web article provides more information on how this test is performed, when you have to be tested, and how food and other medications may affect your reading.)