INR is also called International Normalized Ratio, the normal range is 0.8-1.3. This index is often tested in clinical practice, mainly to predict whether the patient is currently taking warfarin to meet the standard, the range of the standard means that the patient’s INR value should range between 2-3. If it exceeds 4, brain hemorrhage or bleeding in other parts of the body can easily occur, which is relatively dangerous. Therefore, in the process of taking warfarin, the INR must be closely monitored, that is, the International Normalized Ratio, this value should be measured once a week in the first month of taking the drug, according to the degree of stability can later be changed to once a month to measure the International Normalized Ratio, which is relatively safe.