Warfarin - Explain PT/INR scale?
- 22 Mar 2012 by Richard Hahn
- warfarin, prevention of thromboembolism in atrial fibrillation
24 Mar 2012
PT means prothrombin time, or "pro-time", is one of the blood tests done to see how fast your blood clots. Prothrombin is a protein produced by the liver that helps blood clot. If you are taking blood thinners, it is done to see how your medicine is working. INR, means international normalized ratio, is used to monitor the effectiveness of anticoagulants such as warfarin. The test result for PT depends on the method used, with results measured in seconds and compared to the average value in healthy people. Most laboratories report PT results that have been adjusted to the International Normalized Ratio (INR) for patients on anticoagulant drugs. These patients should have an INR of 2.0 to 3.0 for basic "blood-thinning" needs. For some patients who have a high risk of clot formation, the INR needs to be higher - about 2.5 to 3.5.
Since you are taking Warfarin your doctor will check your PT/INR regularly to make sure that your prescription is working properly and that your PT/INR is appropriately prolonged. There is no set frequency for doing the test. Your doctor will order them often enough to make sure that the drug is producing the desired effect - that it is increasing your clotting time to a therapeutic level without causing excessive bleeding or bruising.
- Warfarin Information for Consumers
- Warfarin Information for Healthcare Professionals (includes dosage details)
- Side Effects of Warfarin (detailed)
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