Prothrombin Time: normal range and what it means
How quickly your blood clots.
Normal range
Adult reference range.
- Low< 11 sec
- Normal11 – 13.5 sec
- High≥ 13.5 sec
What it measures
How long your blood takes to clot along one particular pathway. It lengthens in liver disease, in vitamin K deficiency and on warfarin.
What moves it
Warfarin, vitamin K intake, liver function and fat absorption. The single most medication-sensitive marker on a routine panel.
How to bring it into range
Usually reported with INR, which standardises it between labs. Vitamin K intake affects it if you take warfarin.
How fast it responds
Days.
Also reported as: pt
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Common questions
- What is a normal Prothrombin Time level?
- Normal: 11 – 13.5 sec. Adult reference range.
- What does a high Prothrombin Time mean?
- A value above the reference band means Prothrombin Time is outside the range typical for a healthy adult. A single reading is rarely conclusive on its own — what matters is the trend across draws and the other markers around it, which is why HealthOS reads the whole panel together rather than one number at a time.
- How do I improve my Prothrombin Time?
- Usually reported with INR, which standardises it between labs. Vitamin K intake affects it if you take warfarin.
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Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.