Which lab value is monitored to assess anticoagulation in patients on warfarin?

The International Normalized Ratio (INR) is the primary lab value monitored to assess anticoagulation in patients on warfarin. Warfarin works by inhibiting vitamin K-dependent clotting factors, which affects the prothrombin time (PT). The PT is transformed into the INR to standardize the results across different laboratories, taking into account variations in testing methods and reagents.

The INR provides a consistent measurement that allows healthcare providers to determine if a patient is within the desired therapeutic range for anticoagulation. This range typically falls between 2.0 and 3.0 for most conditions, but it may vary depending on the specific indication for anticoagulation. By monitoring the INR, clinicians can adjust warfarin dosages effectively to maintain the appropriate level of anticoagulation, minimizing the risk of thromboembolism or bleeding complications.

Other lab values such as APTT are not typically used for monitoring the effects of warfarin; they are primarily used for heparin therapy instead. A platelet count measures the number of platelets in the blood, which is important for evaluating bleeding disorders but is not directly related to warfarin therapy. Thus, the correct focus on the INR for monitoring anticoagulation in