what is an INR involve
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®).omeone who is not taking warfarin would compare their PT test result to the normal range provided with the test result by the laboratory performing the test. A prolonged PT means that the blood is taking too long to form a clot.