What is a PT/INR test?
A prothrombin time test is a blood test used to evaluate blood clotting. INR stands for international normalized ratio, a calculation that expresses the results of the time test.
Prothrombin is a protein made by the liver to assist in blood clotting. Blood clotting helps stop bleeding when you get a wound, but may also lead to blockage in an artery or vein. This can cause a stroke, heart failure, or heart attack. Your doctor may order a coagulation panel if they suspect you may have a condition that affects your body’s normal blood clotting functions. Conditions that may be diagnosed through a PT/ INR test include:
- Hemophilia (a bleeding disorder that may result in spontaneous bleeding)
- Thrombosis (blood clots causing a blockage in blood vessels)
- Liver disease
- Vitamin K deficiency
In addition to screening for these blood clotting conditions, a PT/INR test is commonly ordered for individuals who take blood-thinning medication such as warfarin. Warfarin is prescribed as a treatment for blood clots.