✍️ Edited by Farhan Ahmed, Editor, MedTestBD · Last updated: August 2026
What is the Prothrombin Time (PT) / INR Test?
The Prothrombin Time (PT) test measures how long it takes for your blood to clot. The result is usually expressed as an INR (International Normalised Ratio), which is a standardised value that makes results comparable across different laboratories. This test is essential for evaluating bleeding and clotting disorders.
Why is the PT / INR Test Done?
- To monitor patients taking blood-thinning medication (anticoagulants) such as Warfarin — ensuring the dose is safe and effective
- To investigate unexplained bleeding, bruising, or slow wound healing
- To assess liver function, as the liver produces the clotting factors measured by this test
- Before surgery, to check if blood clotting is normal
- To diagnose clotting disorders such as haemophilia or vitamin K deficiency
Normal PT / INR Levels
| Group | Normal Range |
|---|---|
| General population (not on anticoagulants) | INR: 0.8 – 1.2 | PT: 11 – 13.5 seconds |
| Patients on Warfarin therapy (general) | INR: 2.0 – 3.0 (target range) |
| Patients with mechanical heart valves | INR: 2.5 – 3.5 (target range) |
A high INR means blood is taking longer to clot, which increases bleeding risk. A low INR means blood may clot too quickly, increasing clot risk. Target INR depends on the reason for anticoagulation.
How to Prepare for the PT / INR Test
- Fasting is not usually required for this test
- Do not stop any blood-thinning medication before the test — the test is designed to monitor your levels while on medication
- Inform the lab about all medicines you take, especially Warfarin, Heparin, Aspirin, or any anticoagulants
- Avoid alcohol before the test if possible, as it can affect clotting results
- If you have liver disease, a bleeding disorder, or recent surgery, inform the lab beforehand
PT / INR Test Price in Bangladesh
PT / INR test prices vary between diagnostic centers across Bangladesh. Compare PT / INR test prices on MedTestBD →
Normal ranges cited on this page are based on MedlinePlus and WHO guidance. Prices are collected from public sources and may change — confirm with the facility before visiting. This information is for general reference only and is not medical advice. Always consult a qualified physician.
