What does INR mean on a blood test?

The blood test result is called the INR (International Normalised Ratio). This indicates to the doctor, pharmacist or nurse looking after you what dose you will need to take. Your dose may vary depending on the INR result. The INR result and warfarin dose will be written in your yellow book.

What is the International Normalized Ratio (INR)?

The international normalized ratio (INR) is a calculation derived from the PT test that helps ensure that test results are standardized from one lab to the next. For people on anticoagulant therapies such as warfarin, the INR should generally be around 2–3, though it might be higher for people at increased risk of clotting. 5

What is the difference between INR and prothrombin time?

INR is close related to the prothrombin time (PT). PT is one of the most important parameters measured in the coagulation screen section of a blood test. The major advantage of the INR system is that it helps alleviate confusion in the interpretation of prothrombin time (PT) results.