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Prothrombin Time with INR
Prothrombin Time with INR
This test may help measure how long it takes for your blood to clot. A healthcare provider may use this to monitor medication in your blood if you are taking warfarin (a type of medication known as a blood thinner which can treat and prevent blood clots). Read moreTest details
Sample type:
Blood
Preparation:
You do not need to do anything special to prepare for the sample collection.
This test does not require fasting.
$39.00
+ $6.00 Physician Service Fee
What
Our PT/INR Test measures how long it takes for blood to clot.
Who
Must be 18+ years of age to purchase.
How
Blood
Schedule an appointment, then visit a Quest Diagnostics patient service center location.
About the Test
Our Prothrombin Time with INR (PT/INR) Test measures how long it takes for your blood to form a clot (coagulate). Anticoagulants (anti-clotting medications) change the way your blood clots. Warfarin is a commonly prescribed anticoagulant, or blood thinner, that prevents blood from clotting. Anticoagulant therapy must be carefully monitored to make sure the dosage is right for the patient; otherwise, severe and persistent bleeding or excessive blood clotting (hypercoagulation) can occur.
How Does it Work?
Take an in-person test at a Quest Diagnostics location.
Over 2000+ locations focus on your safety, confidentiality and convenience.
1. Purchase your test
Schedule your appointment after purchasing a test to minimize wait time.
2. Visit a location
Enter your zip code to find a Quest Diagnostics location closest to you.
3. Get results online
We will email you when your confidential results are available.
Take an in-person test at a Quest Diagnostics location.
Over 2000+ locations focus on your safety, confidentiality and convenience.
1. Purchase your test
Schedule your appointment after purchasing a test to minimize wait time.
2. Visit a location
Enter your zip code to find a Quest Diagnostics location closest to you.
3. Get results online
We will email you when your confidential results are available.
What to expect with Quest

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Get lab work without having to wait and pay for an appointment with a doctor. Shop questhealth.com and choose from 75+ tests – the same quality tests that doctors use and trust, but no doctor visit required for purchase.

Easy to buy & simple to schedule
After your purchase, schedule an appointment at a nearby Quest Diagnostics location and have your specimen sample collected by a trained healthcare professional.

Fast online results, with support
Access test results from your phone as soon as they’re available, with the option to discuss your results with an independent physician at no extra cost.
FAQs
Yes, this test is also called PT with INR, protime INR, protime with INR, and prothrombin time/international normalized ratio.
Anticoagulants are often called blood thinners, but do not actually change the consistency of the blood. These medications make it harder for blood clots to form in the heart, veins, and arteries and help prevent existing clots from getting larger. Antiplatelets like aspirin are another type of blood thinner which helps prevent platelets from clotting and are usually given to people with a history of heart attack or stroke.
Vitamin K helps the body create blood clots and slow bleeding. Warfarin functions as a vitamin K antagonist (blocker) by interfering with the liver's conversion of vitamin K, causing the blood to clot more slowly.
If your test result is showing lower or elevated PT/INR values, you should contact your healthcare provider right away to establish next steps of care.