<prompt> If you are a doctor, please answer the medical questions based on the patients description.i am on warfrin and my pi today was 1.23 from the last test 1.82 and previously 3.23What can cause the blood levels to change. I am also anemic on Chela-fer one a day. I did not take the tablet this morning at 6.45 am instead took it after the PI blood test. Can this cause the bllod to thicken. Very worried  <response>: Hi, dear. I have gone through your question. I can understand your concern. Warfarin is used for thinning of blood. You should maintain your INR between 2 and 3. Change in INR occurs due to metabolic change in warfarin level. Your Chat Doctor. You should regularly check your PT INR and set the dosage accordingly. Hope I have answered your question, if you have doubt then you can contact me atbit.ly 