Prothrombin time / INR
Also written: PT / INR
What it measures
How long blood takes to clot through one pathway, standardised as INR so results compare across laboratories.
Why it is ordered
Monitoring people on vitamin-K antagonist anticoagulants, assessing liver function, and checking before procedures with bleeding risk.
How to prepare
Usually no fasting. State the time of your last anticoagulant dose — the timing relative to the sample affects interpretation.
Units
INR: không đơn vị · PT: giây — convert here
What to ask
- What is my target INR range
- How often must this be rechecked
- Which foods and medicines shift this number
This page does not include reference ranges and does not say whether your number is high or low. Reference ranges differ between laboratories and between people — read yours on your own report, with your clinician.