When monitoring a patient on warfarin, which of the following should be closely observed?

Monitoring a patient on warfarin is crucial because it is an anticoagulant that can significantly increase the risk of bleeding. Close observation for signs of bleeding and bruising is essential, as these might indicate that the patient's INR (International Normalized Ratio) levels are too high, leading to an increased risk of hemorrhage.

Additionally, dietary Vitamin K intake needs careful monitoring, as Vitamin K can counteract the effects of warfarin. Patients on warfarin should maintain a consistent intake of Vitamin K in their diets, as fluctuations can directly impact anticoagulation control. This is why bleeding, bruising, and Vitamin K intake are critical elements to observe when managing a patient on warfarin.

While blood pressure and heart rate are important factors in overall patient assessment, they are not specific indicators of warfarin therapy management. Liver function tests and kidney function, while significant due to their potential impact on drug metabolism and clearance, do not directly pertain to the immediate risks associated with warfarin therapy, such as coagulation status and bleeding. Thus, the focus on bleeding, bruising, and Vitamin K intake appropriately highlights the primary concerns in monitoring a patient on warfarin therapy.