Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.
What the test is
INR standardizes results so they can be compared between labs. Home finger-stick meters are available for some people on warfarin.
Why it's done
- Adjusting warfarin doses
- Before surgery
- Bleeding or bruising problems
- Liver disease
Getting ready and what happens
- Tell your provider about all medicines and supplements; many affect INR.
How the test is done
- A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.
- Some clinics use a finger-stick meter.
What the results mean
| Result | Typical range for adults |
|---|---|
| Not on blood thinners | INR about 0.8 to 1.1 |
| Usual warfarin goal | INR 2.0 to 3.0 (2.5 to 3.5 for some heart valves) |
Normal ranges vary from lab to lab and can differ by age, sex, and pregnancy. Your report lists your lab's own range next to each result. A result a little outside the range is often not a problem.
Higher than goal
Raises bleeding risk. Your warfarin dose may be lowered or held.
Lower than goal
Raises clot and stroke risk. Your dose may be raised.
High without warfarin
Can point to liver disease or low vitamin K.
When a result needs quick action
Call 911Bleeding that won't stop, vomiting blood, a severe headache, or a fall with a head injury while on warfarin
Call your provider todayAn INR much higher than your goal, even without bleeding
Questions to ask your provider
- What do my results mean for me?
- Do I need to repeat this test or have other tests?
- What's my INR goal?
- How often should I be tested?
- What foods and medicines affect my INR?
Risks
A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.
Related conditions
Related medicines
Related tests
Sources
Last updated 2026-11-13.