What Is the Normal INR Range?

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The international normalized ratio ranges between 0.8 and 1.1 for a person who is not taking anticoagulant medication, explains MedlinePlus. Patients on blood-thinning medicines have a target international normalized ratio of between 2.0 and 3.0, states Mayo Clinic.

The American Association for Clinical Chemistry explains that the international normalized ratio standardizes the prothrombin time test results by compensating for differences between laboratory reagents. The prothrombin time test, which measures the blood plasma clotting speed, is used to investigate potential bleeding disorders or to monitor liver problems. The prothrombin time is also measured in seconds; the normal range is between 11 and 13.5 seconds, according to MedlinePlus.