A patient receiving heparin therapy develops a platelet count of 120,000/mm3 (normal: 150,000-450,000) and presents with red and swollen legs. The nurse suspects Heparin-Induced thrombocytopenia. What is the nurse's priority action?

A. Continue heparin therapy and monitor platelet counts: Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse reaction in which antibodies form against the heparin–platelet factor 4 complex, leading to platelet activation and thrombosis. Continuing heparin can worsen platelet consumption and increase the risk of life-threatening thromboembolic events. B. Discontinue heparin immediately and start an alternative anticoagulant: The priority intervention in suspected HIT is the immediate cessation of all heparin products to prevent further antibody-mediated platelet activation. Because HIT creates a prothrombotic state, an alternative non-heparin anticoagulant is initiated to reduce the risk of DVT or PE. C. Administer platelet transfusion to manage thrombocytopenia: In HIT, thrombocytopenia results from platelet activation and consumption, not from decreased production. Transfusing platelets may exacerbate thrombosis by providing additional substrate for clot formation. Platelet transfusions are generally avoided unless there is significant active bleeding. D. Administer intravenous fluids to prevent dehydration: While maintaining adequate hydration is important for overall circulatory stability, IV fluids do not address the immune-mediated platelet activation or thrombotic risk associated with HIT. The immediate threat is thrombosis, which requires stopping heparin and initiating alternative anticoagulation.