The INR, also known as the International Normalized Ratio, is a routine coagulation test with a normal reference value of 0.8-1.5. The INR is used clinically to monitor the dose of oral anticoagulants for the treatment of thrombotic disorders, and the World Health Organization has established a reasonable range of 2-4 for the application of oral anticoagulants, i.e., a mildly anticoagulated state. When the INR is greater than 4, an appropriate reduction in the anticoagulant drug dose is required. When INR is less than 2, it is necessary to increase the dosage of drugs appropriately to achieve a state of mild anticoagulation of the blood and prevent the regeneration of blood clots.