PT (INR) Value normal range — check your value
About 0.8 to 1.2 for someone not on blood thinners. Those on warfarin are usually kept between 2.0 and 3.0, depending on why it was prescribed.
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Your PT (INR) Value test value
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What PT (INR) Value measures
Prothrombin time standardised across laboratories, used to monitor warfarin and assess liver clotting function.
PT (INR) Value normal range chart
These bands are for female, 18 years and above. Enter your age and gender above to see the bands for you. The table below shows the range for every age and gender.
PT (INR) Value normal range by age and gender
What a high PT (INR) Value means, and common causes
A high INR means blood is clotting more slowly than intended and bleeding risk is raised. Above 5 it usually needs same-day medical attention.
Common causes: Too much warfarin, interactions with antibiotics and many other medicines, liver disease, vitamin K deficiency, and alcohol.
What a low PT (INR) Value means, and common causes
A low INR in someone taking warfarin means the dose is not protecting them enough and clot risk remains.
Common causes: Too low a warfarin dose, missed doses, and a sudden increase in vitamin K rich foods such as spinach and other green leafy vegetables.
Frequently asked questions
Please note. This page explains what a number means against reference ranges for your age and gender. It does not diagnose anything, cannot see the rest of your report, and is no substitute for a doctor. If your lab’s printed range differs, your lab’s range applies.