The Heart and Vascular Clinic Nashville, TN

What Is A PT/INR Test?

A PT (prothrombin time)/INR (international normalized ratio) test is a test that evaluates how well and how quickly blood clots.

When Might I Need A PT/INR Test?

PT/INR tests are typically conducted to identify:

  • Why a Patient Is Bleeding Or Bruising Easily Or Excessively
  • If a Medication Is Working (Blood-Thinning Medication like Warfarin)
  • If a Patient Has a Lack Of Blood Clotting Factors (Like Prothrombin)
  • A Vitamin K Deficiency
  • Liver Function
  • The Rate At Which The Body Uses The Clotting Factors

These tests are generally used:

  • Before Surgery (To Evaluate Your Body’s Ability To Clot)
  • When Taking a Blood-Thinner Like Warfarin (To Evaluate Effectiveness)
  • When a Patient Shows Signs Of Excessive Bleeding/Blood Disorder

What Should I Expect?

When having a PT/INR test, you will have blood drawn, most likely from your arm or finger. If having a blood sample taken from your arm, the sample will typically be evaluated by a lab for INR levels. If a finger-prick method is used, you may find out your INR levels within minutes. Either way, your doctor will discuss your INR levels with you and what they say about your body’s ability to clot blood.

How Should I Prepare For The Procedure?

It is incredibly important to discuss PT/INR test preparation with your doctor. There are some common foods, drinks and medications that can interfere with test results, so be sure to ask what you should avoid beforehand.

If you have any questions about PT/INR testing, please discuss them with your doctor during your next scheduled appointment.

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