Heparin-associated thrombocytopenia

• Seen in 5% of adults getting unfractioned heparin; rare in those on LMWH

• Associated with 2 kinds of thrombocytopenia

  • Type I

    • More common variant; onset rapidly after starting heparin therapy

    • This is modest in severity and is clinically insignificant

    • This is a result of the direct platelet aggregating effects of heparin

  • Type II

    • Much more severe; typically starts 5-14 days after starting heparin therapy

    • This is due to the production of circulating Abs to a heparin/platelet factor 4 complex

      • Abs bind to those complexes on platelets and endothelial cells resulting in platelet activation and endothelial damage

      • Systemic platelet aggregation leads to life-threatening venous and arterial thrombosis and infarction

• People getting heparin therapy should always be watch for thrombocytopenia

• Treatment involves stopping the unfractioned heparin and using LMWH or another anticoagulant

Category: Medical Subject Notes , Pathology Notes