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Interpreting the International Normalized Ratio

Typically, a healthy person who is not taking a blood-thinning medicine will have an INR of about 1 (the usual range is from 0.8 to 1.2). A person taking warfarin will generally have a higher INR value. As the warfarin dosage is increased, a person's INR should also increase. The higher the INR, the longer it takes the blood to clot. This can help prevent blood clots that may lead to strokes. However, if the INR is too high, there is a risk for uncontrolled bleeding.
Recommended target INR and goal ranges are based on a person's reason for taking the medication. These ranges are as follows:
  • 2 to 3 -- the typical range for most "blood-thinning" needs
  • 2.5 to 3 -- the desired range for people who have a high risk for developing a blood clot.
Talk to your healthcare provider if you have questions about your own personal INR goal range. Ranges are individualized according to your particular medical history.
Your healthcare provider will use your international normalized ratio to adjust your anticoagulant dosage. Do not adjust your dose unless your healthcare provider specifically tells you to do so.

How Often Should INR Be Checked?

When a person begins taking an anticoagulant medication, the INR value is checked frequently (two to three times per week). Once a person is stabilized on the medicine, INR tests are generally less frequent (ideally once or twice per month).
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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