what is an INR
The international normalized ratio (INR) is a calculation based on results of a PT and is used to monitor individuals who are being treated with the blood-thinning medication (anticoagulant) warfarin (CoumadinÂ®).he INR can be used to adjust a person's drug dosage to get the PT into the desired range that is right for the person and his or her condition. Warfarin may be prescribed for conditions such as: 1  Irregular heartbeat (atrial fibrillation). 2  The presence of artificial heart valves.