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Protime and International Normalized Ratio (PT/INR) / Anti Coagulation Therapy Blood Test

* This is not a home test kit. You will need to visit a local lab for testing.

Also Known As

Prothrombin Time/International Normalized Ratio, PT Protime

The Purpose of an INR Blood Test

Prothrombin is a coagulation factor that is essential for proper blood clotting. Produced by the liver, balanced prothrombin levels ensure that you don’t bleed excessively from a wound and help prevent abnormal, potentially life-threatening clots from forming in your body and blocking blood flow. If you are suffering from unusual bleeding or blood clots, you may take an INR blood test (international normalized ratio). Your physician may also use this test to monitor your health if you are on anticoagulant therapy such as heparin or warfarin.

Prothrombin Time (Protime) and International Normalized Ratio (PT/INR) (8847)
Prothrombin Time (Protime) and International Normalized Ratio (PT/INR) (005199)

What Does the PT Blood Test Measure?

The protime blood test assesses how long it takes your blood sample to clot. The INR measurement is derived from that result. This test may also be taken with a partial thromboplastin time blood test for a fuller picture of clotting activity.

Who Should Take a Protime Blood Test?

You may consider taking a PT blood test if you have unexplained bleeding or are on blood-thinning medication. Frequent bruising and nosebleeds may be signs of a bleeding disorder, while leg swelling or pain, chest pain, and elevated heart rate may be your early warning signs of a clotting problem.

INR Lab Test Preparation

Fasting isn’t required for the PT/INR test. Check with your doctor about special test prep instructions if you are on an anticoagulant, as you may need to give your blood sample before taking your medication that day.

PT/INR Test Results

Normal INR results should be 1.0 for people who aren’t on blood thinners. Patients on anticoagulant therapy will want their levels to fall between 2.0 and 3.0.

Where Can I Get a Prothrombin Time Test Near Me?

At Personalabs, the INR lab test is one of more than 400 health tests you can shop for online, including a comprehensive selection of general wellness tests. You’ll enjoy the ease and convenience of our ordering process:

Step 1: Purchase your test, which comes with a lab order that you’ll need to download to complete your testing. (A doctor’s pre-approval may not be required before buying a test, which depends on the state where you live.)

Step 2: Pinpoint the lab closest to you with our locator tool. Our partnerships with Quest Diagnostics and Labcorp give you access to more than 4,000 facilities across the country.

Step 3: Get your blood drawn at the lab. (Be sure to bring your downloaded test order.)

Step 4: Check your confidential Personalabs portal to get your results within 24 to 48 hours, excluding weekends. Contact us if you need us to reach out to the lab about delivering the test results by a specific date. Need more help? Arrange a telehealth visit with a Personalabs doctor.

A preventive and proactive approach to health is essential for a vibrant life. Ordering tests from Personalabs gives you control over your health, with measurable data that you can use to create actionable steps toward leading your best possible life. Shop our test collections today.

Additional information


LabCorp, Quest

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Visit the Lab

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Get Your Results

Results can be provided in as little as 24-48 hrs. For more complex tests, please contact us for turn around times.


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