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PT and INR

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Also known as: Prothrombin Time; Pro Time; Protime
Formal name: Prothrombin Time and International Normalized Ratio

At a Glance

Why Get Tested?

To check how well the blood-thinning medication (anticoagulant) warfarin (COUMADIN®) is working to prevent blood clots; to help detect and diagnose a bleeding disorder

When to Get Tested?

When you are taking warfarin or when your doctor suspects that you may have a bleeding disorder

Sample Required?

A blood sample drawn from a vein in the arm; sometimes blood from a fingerstick

Test Preparation Needed?

None needed, although if you are receiving anticoagulant therapy, the specimen should be collected before taking your daily dose.