Prothrombin Time with INR

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Prothrombin Time with INR


Test Description

The Prothrombin Time Test is used to detect and diagnose excessive clotting disorder or bleeding disorder. And the International Normalized Ratio (INR) calculates the PT results and monitor how the anticoagulant Warfarin is working to prevent blood clotting.
What is being tested?
In the Prothrombin Time test, the body's ability to form blood clots is tested. Then the INR is calculated that decides the amount of medication. A Prothrombin Time with INR Test measures how much time the proteins take to work as coagulators. Whenever a person is injured and bleeds, hemostasis begins, which is the clotting process. It is done by the coagulation factors, which are usually normal in a healthy human being. These factors kick in and form a clot in the place of injury to prevent excessive loss of blood. PT is measured in seconds, and then it is compared to the normal range of clotting. As various labs and clinics and hospitals use different reagents, the normal rate at which clotting happens fluctuates. Hence, WHO has standardized the system with the help of the International Normalized Ratio or INR, as you know.
How is the test used?
The Prothrombin Time with INR Test is used to monitor the effectiveness of the anticoagulant Warfarin, which is given to a person. Warfarin is prescribed to people who suffer from conditions that make the blood thinner than normal and prevents clotting. Hence, the healthcare provider recommends this test to calculate the dosage using the PT/INR test. The dose will be adjusted according to the results to ensure that it is sufficient to support blood clotting when necessary, and prevent excessive bleeding.
Warfarin is prescribed for conditions such as:

  • Irregular Heartbeat (atrial fibrillation)
  • People who have artificial heart valves
  • Deep vein thrombosis (DVT), pulmonary embolism (PE)
  • Antiphospholipid Syndrome
  • Occasional heart attacks with certain risk factors

  • When is the test ordered?
    The Prothrombin Time with INR Test will be ordered frequently for the person who is taking anticoagulant drug warfarin to get the desired effect. If you are having one of the following symptoms, then the test is ordered:
  • Unexplained bleeding or easy bruising
  • Nosebleeds
  • Bleeding gums
  • A blood clot in vein or artery
  • Acute conditions like DIC
  • Chronic Conditions such as liver disease that may affect hemostasis.

  • Test Results:
    When the Prothrombin Time with INR Test is prescribed, the dosage of Warfarin is calculated. For the people who have a risk of a blood clot, the INR needs to be higher than 2.5 to 3.5. For the people who are not taking Warfarin, the range of PT results vary from lab to lab. A prolonged PT means that the blood is taking longer than necessary to form a clot. This might be happening due to conditions such as liver disease, Coagulation factor deficiency, or vitamin K deficiency. Combined with the PTT test, the results can help identify and treat various conditions.
    Testing Info

    Alternate Name: Prothrombin Time with INR Blood Test

    Test Instructions : Please do not exercise prior to testing. It is best that your blood is taken in a rested state.

    Fasting: No

    Methodology: Photo-Optical Clot Detection

    Results In: 2

    Note: Turn around times on results are an estimate and are not guaranteed. The lab may need additional time due to holidays, confirmation/repeat testing, etc. You can contact us to discuss when your results should be ready and we will contact the lab on your behalf immediately.