What it means
The INR comes from the prothrombin time (PT). Because each lab's PT test differs a little, the result is converted to the INR so that the number means the same thing everywhere. A higher INR means the blood takes longer to clot. It is used mainly to adjust the dose of warfarin, and also to check liver function, since the liver makes clotting factors.
For the nurse
Check the INR before giving warfarin and report a value above the target. Watch for bleeding: gums, nosebleeds, bruising, blood in urine or stool. phytonadionefy-toh-nuh-DY-ohnVitamin K1 given as a drug, by mouth or injection, to help the blood clot.Full entry reverses warfarin.
At a glance
| Normal range | About 0.8–1.1 for a person not taking an anticoagulant (it has no units). The usual target on warfarin is 2.0–3.0; some conditions, such as mechanical heart valves, use a higher target. |
|---|---|
| Abbreviations | INR; PT (prothrombin time) |
| Also written | INR, PT/INR |
Related terms
anticoagulant
A drug that slows the blood's ability to form clots.
hepatic
Relating to the liver.
clotting
The process by which blood thickens into a gel to plug a damaged vessel and stop bleeding; also called coagulation.
phytonadione
Vitamin K1 given as a drug, by mouth or injection, to help the blood clot.