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INRratio
INR standardises the prothrombin time so results compare across labs. It is the main test for warfarin monitoring.
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What INR measures
INR standardises the prothrombin time so results compare across labs. It is the main test for warfarin monitoring.
If your INR is low
An INR below the range on warfarin means less anticoagulation than intended; otherwise it is rarely notable.
Commonly associated with
- Missed doses of warfarin
- Dietary vitamin K changes
If your INR is high
An INR above the range means the blood is clotting more slowly; on warfarin the target range is set individually and is usually 2–3.
Commonly associated with
- Warfarin
- Liver function
- Low vitamin K
- Antibiotic interactions
Typical reference range
| Group | Typical range |
|---|---|
| Adults | 0.8 – 1.2 ratio |
Typical adult values used by many US labs. Your own report prints the range your lab validated for its method, and that range is the one that counts. Labwise always uses the printed range first.
If it is within range
Your INR is within the range printed by your lab.
Also listed as
INTERNATIONAL NORMALIZED RATIO, PT/INR
Related tests
This page is general information about what a laboratory test measures and what results outside a reference range are commonly associated with. It is not medical advice, does not diagnose any condition and does not replace your clinician. Discuss your results with your healthcare provider.