Which laboratory test must a client taking warfarin have monitored regularly?

The International normalized ratio (INR) is the laboratory test that must be monitored regularly in clients taking warfarin. Warfarin is an anticoagulant that is used to prevent blood clots, and it works by inhibiting vitamin K-dependent clotting factors. Because of its narrow therapeutic index, it is crucial to ensure that the dosage of warfarin remains within a safe and effective range to minimize the risk of thromboembolism and bleeding complications.

The INR provides a standardized measurement of how well anticoagulation therapy is working by comparing the patient’s prothrombin time to a normal range, allowing for consistent monitoring across different laboratories. Regular INR monitoring helps healthcare providers adjust the warfarin dose as needed, ensuring proper anticoagulation levels and improving patient safety.

In contrast, while a complete blood count could provide information on blood components and liver function tests might assess the safety and effectiveness of medication metabolism, neither is specifically designed to monitor the effectiveness and safety of warfarin therapy. The prothrombin time is related to INR but is not as standardized for monitoring warfarin treatment because it can vary between laboratories. Therefore, the INR is the critical test for patients on warfarin.