INR Clinic

What is an INR test?

The INR test (International Normalized Ratio) is a blood test that measures how long it takes blood to clot. This test can be used to check for bleeding problems and/or check whether anti coagulation medicine is working. This test is especially important before a surgery is due, to find out the extent of which blood clots occur. The INR test is usually offered to:

  •  Detect a bleeding disorder
  •  Diagnose liver problems
  •  Screen people having surgery for unrecognized bleeding problems
  •  Patients on anticoagulation medication

Preparation for the procedure

To ensure the effectiveness of the Warfarin / Coumadin therapy that is determined by the INR test, consistency and moderation in dietary intake of vitamin K needs to be maintained. If you are taking any prescription medications (especially antibiotics) or non-prescription medications, including herbal or dietary supplements, they may affect the results of the test; Please make sure that you tell your doctor about medications that you are taking.


The INR test is very straightforward, a single drop of blood is drawn by a finger prick and the results are obtained in less than 30 seconds. Results for this test are determined in the form of numbers. The ideal range will vary by individual depending on a variety of factors including medical conditions, reason for taking anticoagulants, etc. Your WCC clinician will determine the appropriate range for you.

  •  5.0 is considered a high INR level indicating the person is likely to start bleeding
  •  0.5 is considered a low INR level indicating the person is at a high risk of getting a clot
  •  The most common INR range for someone on Warfarin is between 2.0 and 4.0

New patients are provided with a complimentary INR test strip, the following tests require the patient to purchase test strips for him/herself.