How Does Fasting Affect INR and %TTR?

A report published in the Journal of Thrombosis and Haemostasis looked at the effects of fasting in Muslim patients taking warfarin. The anticoagulation medication warfarin is influenced by changes in the diet and fasting might influence the INR and the %TTR. During the month of Ramadan, when Muslims fast during daylight hours (about 13.5hrs/24), stable warfarinised Muslim patients had their INR level tested before, during, and after Ramadan. Unsurprisingly the INR measurement and %TTR changed. The study concluded that fasting significantly increases the mean INR of medically stable patients taking warfarin and the likelihood of having an INR above therapeutic targets.

Source: The effects of fasting in Muslim patients taking warfarin