What lab value is critical to monitor in patients on Warfarin therapy?

Monitoring prothrombin time (PT) and the International Normalized Ratio (INR) is crucial for patients on Warfarin therapy because Warfarin is an anticoagulant that works by inhibiting vitamin K-dependent clotting factors. The INR is specifically used to evaluate the effectiveness and safety of Warfarin, providing a standardized measure of blood coagulation.

Patients taking Warfarin require regular INR testing to ensure that their blood coagulation levels remain within a therapeutic range. This helps to prevent both thromboembolic events (if the INR is too low) and serious bleeding complications (if the INR is too high). Maintaining the INR within the prescribed therapeutic range is vital for effective management of conditions like atrial fibrillation, deep vein thrombosis, and pulmonary embolism.

While hemoglobin levels, platelet counts, and liver function tests provide valuable information regarding a patient's overall health and potential risks of bleeding or clotting, they do not directly reflect the anticoagulation status in patients receiving Warfarin. Therefore, PT and INR are the most critical lab values to monitor in this context.