I have had A-FIB for at least 30 years. I am now 72 years of age. I am on the drug Warfarin and up until about a month ago my blood count numbers were ok as per my Dr. My IandR is now 1.8 and my PT is 17.7 Where should my numbers be ? Does Warfarin effect both my IandR and PT ? What does IandR and PT stand for ?