Prothrombin Time with INR
Also known as: PT
Use
The Prothrombin Time with INR (PT/INR) test measures how long it takes for blood to form a clot, with results standardized as the international normalized ratio (INR). It is commonly used to monitor anticoagulant therapy such as warfarin to ensure appropriate dosing and prevent bleeding or excessive clotting, and may also be used to evaluate bleeding or clotting disorders, vitamin K deficiency, or liver disease.
Special Instructions
No special preparation is required for the test.
Limitations
Results may be affected by pre‑analytical variables such as underfilled, uncapped, or expired collection tubes, hemolysis, and clotted or partially clotted specimens due to improper mixing after collection ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/faq104?utm_source=openai)).
Methodology
Other
Biomarkers
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
Blood
Patient Preparation
No special preparation is required.