18/09/2026
INR = International Normalized Ratio.
defn-It is a blood test that measures how long your blood takes to clot, standardized from the PT (prothrombin time) test. It is especially used to monitor warfarin treatment.
Typical INR ranges
* Not taking anticoagulants: about 0.8–1.1/1.2
* Most patients taking warfarin: target 2.0–3.0
* Some mechanical heart-valve patients: may require a higher target, depending on the valve and clinical situation.
- High INR: blood clots more slowly → increased bleeding risk.
- Low INR: blood clots more quickly → increased risk of thrombosis.
