Which laboratory test is commonly used to monitor patients receiving coumarin (warfarin) treatment?

Explanation

For patients on coumarin (warfarin) therapy, the prothrombin time (PT) is the preferred test to monitor anticoagulation effectiveness. Partial thromboplastin time (PTT) is typically used for heparin monitoring, while bleeding time and capillary fragility tests assess platelet function and vessel integrity, respectively.