I have been on warfarin for three weeks since my pulmonary embolism. initially I was on lovenox ( x. 1 week) and warfarin. since stopping the lovenox my physician has steadily increased my warfarin to 10 mg/day, yet my pt/inr has not come up well, still around 1.64. i have avoided the green leafy veggies, broccoli etc. no source for the clot was found. is it unusual to have this kind of difficulty to achieve a therapeutic range for pt/inr?