I just got a call to stop taking my warfarin because i had a "critical inr" this morning. what does that mean?

Level is too high: Inr tells us how effectively your warfarin is thinning your blood. Generally a level between 2.0 and 3.5 is considered ok depending on the problem. If it gets too high, the risk of bleeding increases and adjustment of the dose is needed. In some cases, stopping the drug is needed temprarally, to reduce the inr before restarting the warfarin at a new dose.

INR too high: Your inr is above a certain level (in my hospital, it is 4.5) where there is a concern over bleeding.

Critical INR: This means that the warfarin in your body is blocking your ability to make a blood clot to the point that you are at risk of bleeding. You could start bleeding a dangerous amount from a minor fall or bump or even start spontaneously bleeding. The spontaneous bleeding could take place internally, which would be very dangerous. Follow your doctor's instructions.