Laboratory test
INR
Other names and abbreviations: prothrombin time, PT, INR
A blood clotting indicator. It monitors treatment with anticoagulants (acenocoumarol, warfarin).
INR shows how quickly blood clots. For people taking acenocoumarol or warfarin, the doctor sets the target range and adjusts the dose.
Typical ranges in adults
| Parameter | Typical range | What a deviation may mean |
|---|---|---|
| INR (without anticoagulants) | 0,8–1,2 | |
| INR (anticoagulant treatment) | usually 2.0–3.0 | target set by the doctor |
The ranges are approximate and differ between laboratories; they also depend on age, sex and pregnancy. A result outside the range doesn't always mean illness – discuss it with a doctor.
When it is done
With anticoagulant treatment, before procedures, with liver disease.
How to prepare
Usually no special preparation is needed. In the morning before the blood draw, it's best not to eat a heavy breakfast – ask at reception.
