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Blood Tests for Those Taking Anticoagulants (Blood Thinners)

When taking an anticoagulant, it is important to have your blood tested for bleeding times to ensure you are taking your medications safely and not at increased risk for bleeding

Prothrombin Time (PT)

Normal range for an adult: 9.9-13 seconds

Preparation

This test may be measured any time of the day without fasting.

PT is a test to determine how fast it takes for your blood to clot. Usually when taking a "blood thinner," such as warfarin (Coumadin), the desired PT is about one and a half times the normal PT. When checking PT, your doctor will receive the results and let you know if you are taking the correct amount of blood thinner medication.

International Normalized Ratio (INR)

Normal level for an adult: 0.9 – 1.2. Your doctor will determine your therapeutic range.

Preparation

This test may be measured any time of the day without fasting.

INR is tested for those on anticoagulant medications to prevent stroke, embolism and heart attack.

Reviewed: 09/13

This information is about testing and procedures and may include instructions specific to Cleveland Clinic. Please consult your physician for information pertaining to your testing.

Talk to a Nurse: Mon. - Fri., 8:30 a.m. - 4 p.m. (ET)

Call a Heart & Vascular Nurse locally 216.445.9288 or toll-free 866.289.6911.

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This information is provided by Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.

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