Why might it be that my coumadin (warfarin) levels go up and down continually?

INR: Coumadin (warfarin) affects certain factors in your blood responsible for blood clotting. While Coumadin (warfarin) prevents these from working properly, they are continually made by your liver and are replenished. This results in the inr going up and down, so your physician needs to adjust your Coumadin (warfarin) dose accordingly. Maintaining a routine diet makes adjusting Coumadin (warfarin) much easier.