I am currently taking a low dose of lisinopril along with an anticoagulant for atrial fibrillation. My creatinine levels were constant or slightly above normal for years, but suddenly - over a period of weeks - have increased to about double (over 300). About a year ago I was switched from Warfarin to one of the newer ones that don't require one t/o have regular INR tests. My concern is my kidney function. Should I drop the lisinopril and switch back to Warfarin?