What parameter should the nurse monitor closely in a patient being treated with heparin?

In a patient receiving heparin treatment, closely monitoring the platelet count is essential due to the risk of heparin-induced thrombocytopenia (HIT). HIT is a serious immune-mediated reaction that can lead to a significant drop in platelet levels, which can increase the risk of thrombosis, despite low platelet counts. By regularly checking the platelet count, the nurse can ensure early detection of HIT, allowing for timely intervention and the adjustment of anticoagulation therapy to prevent complications.

While monitoring blood pressure and heart rate is important for overall patient assessment and might indicate changes in the patient's condition, they are not specific parameters affected by heparin therapy. The International Normalized Ratio (INR) is also not directly monitored in patients on heparin, as this measure is primarily relevant for warfarin therapy. Therefore, the platelet count remains the critical parameter to observe in patients undergoing treatment with heparin.