Prothrombin Time

The prothrombin time is a blood test to determine the adequacy with which the blood can clot in a person. The international normalized ratio (INR) is a calculation based off the prothrombin time to check the ability to clot blood in people who are on blood-thinning medication such as warfarin. This test is used in the evaluation of people who have unexplained bleeding or inappropriate clot formation, as well as to monitor the levels of warfarin in order to determine warfarin toxicity.

This test is performed in following conditions such as:

• Unexplained bleeding or easy bruising
• Nosebleeds
• Bleeding gums
• A blood clot in a vein or artery
• An acute condition such as disseminated intravascular coagulation (DIC)
• A chronic condition such as severe liver disease that may affect hemostasis
• People on warfarin or other anticoagulation medication

Also Known As: PT INR