We present important laboratory testing and clinical management strategies used to safely discharge home a 69-year old woman with heparin-induced thrombocytopenia (HIT) from the hospital. She was admitted for a coronary artery bypass graft procedure for which she was anticoagulated with heparin. Shortly after the procedure she developed thrombocytopenia and was diagnosed with HIT using the 4Ts scoring system, a latex-enhanced immunoassay (LEI) screen and confirmatory serotonin release assay. Her anticoagulation was switched from heparin to argatroban, and response to treatment was monitored in the laboratory using LEI. Unfortunately, she also received platelet transfusions and subsequently developed multifocal deep vein thrombosis with worsening platelet counts with nadir less than 10 x 10^3/μL. After five therapeutic plasma exchange procedures we noted an improvement in platelet counts, which plateaued into the 50s x 10^3/μL. Furthermore, the LEI remained positive. At this juncture we decided to transition from argatroban to fondaparinux so that she could leave the hospital in stable condition. Upon follow-up with hematology she exhibited no worsening clinical signs or symptoms of disease, and platelet counts markedly improved to within normal limits of detection. In this report we examine the utility of LEI in monitoring patients with HIT, therapeutic plasma exchange in the management of severe HIT (with thrombosis), and the use of subcutaneous fondaparinux in managing HIT in the outpatient setting.
Keywords: Fondaparinux; Heparin/adverse effects; Plasmapheresis; Platelet factor 4; Platelet function tests/methods.
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