High INR on warfarin.

A 72 year old woman, who had been diagnosed as having recurrent deep vein thrombosis six weeks earlier, attends the practice’s phlebotomy clinic for an international normalised ratio (INR) check. Her INR is greater than 8.0 (target INR range: 2.0-3.0). During the consultation, you look through her previous INR readings and notice they have been supra-therapeutic over the past two weeks despite a reduction in the dose of warfarin. What you should cover