Prothrombin INR

General Information

Reference Range

Female		Male
Age	Range	Age	Range
0-	0.8-1.3	0-	0.8-1.3

Effective date: 05/17/2010

Ref. Range Notes

Critical Prothrombin time is the PT that generates an INR of 5.0 or higher.

Warfarin Therapy:

INR 2-3: stroke prevention in atrial fibrillation; mechanical aortic valve replacement; prevention and treatment of venous thromboembolism

INR 2.5-3.5: mechanical mitral valve replacement; recurrent venous or arterial thrombosis despite therapeutic anticoagulation

For more information, see web link above labeled “UW Medicine Anticoagulation Service”