Recognizing Hit in a Thrombocytopenic Patient Post-Heparin Drip

When a patient with a history of pulmonary embolism and a femur fracture develops a new thrombus following heparin administration and thrombocytopenia, hepatitis-induced thrombocytopenia (HIT) should be suspected. HIT is characterized by a decrease in platelets by 50% or more, new thrombosis, and skin necrosis at heparin injection sites. The pathophysiology involves antibodies against platelet factor 4 heparin complex, causing arterial and venous thrombosis. A 4T score is used for risk stratification, and a prompt evaluation with ELISA and functional platelet assays is crucial. Anticoagulation should be switched to non-heparin agents like argatroban or bivalirudin in the critically ill and fondaparinux or direct oral anticoagulants in stable patients.