Which laboratory value is most important to monitor in a patient receiving warfarin?

Monitoring prothrombin time (PT) is crucial for patients receiving warfarin because this anticoagulant works by inhibiting vitamin K-dependent clotting factors, which in turn affects the blood's coagulation pathways. The PT measures the time it takes for blood to clot, providing an indication of how well warfarin is working and the risk of bleeding.

In managing warfarin therapy, healthcare providers often monitor PT along with the international normalized ratio (INR), which standardizes PT values regardless of the testing method used. The therapeutic INR range for most indications is generally between 2.0 and 3.0, though it can vary based on the specific condition being treated.

Keeping PT/INR within the therapeutic range is vital to prevent adverse outcomes such as thrombosis if the levels are too low or excessive bleeding if they are too high. Thus, this laboratory value directly correlates with the safety and efficacy of warfarin therapy.

While monitoring blood glucose, creatinine levels, and white blood cell count can be important in other contexts, they are not directly related to the management of anticoagulation therapy with warfarin.