After heparin therapy, which test should be monitored regularly following discharge with warfarin (Coumadin)?

Warfarin (Coumadin) therapy requires careful monitoring to ensure effective anticoagulation while minimizing the risk of bleeding. The Prothrombin Time (PT) and its derived International Normalized Ratio (INR) are critical for this purpose. PT/INR is a test that measures how long it takes for blood to clot, which is essential in managing patients on warfarin.

Monitoring PT/INR levels allows healthcare providers to adjust the warfarin dose based on the individual's response to the medication. The therapeutic INR range typically depends on the condition being treated but commonly falls between 2.0 to 3.0 for many indications. Regular monitoring helps to ensure the patient remains within this range, maintaining effective anticoagulation and minimizing the risk of thrombosis or hemorrhage.

The other options are less appropriate for monitoring warfarin therapy. A perfusion scan does not provide information about coagulation status; it is used to evaluate blood flow in the lungs or other organs. Activated Partial Thromboplastin Time (APTT) is more relevant for monitoring heparin therapy rather than warfarin, as it assesses the intrinsic pathway of coagulation, which is not predominantly affected by warfarin. Serum Cou