Prothrombin Time Test

Why is INR used alongside PT?

INR standardizes PT results across different labs, reagents, and testing methods, which is especially important for patients on long-term warfarin who may be tested at different facilities over time.

How often is this test needed if I'm on warfarin?

This varies based on how stable your INR has been, ranging from weekly during initial dose adjustment to monthly once your levels are consistently within target range.

Can diet affect my PT/INR results?

Yes, foods high in vitamin K, such as leafy green vegetables, can affect warfarin's effectiveness and shift your INR, so consistency in your diet is generally recommended if you're on this medication.