Thrombocytopenia Calculator 4Ts Score for Heparin-Induced Thrombocytopenia Thrombocytopenia Platelet count fall >50% AND platelet nadir ≥20 Platelet count fall 30–50% OR platelet nadir 10–19 Platelet count fall <30% OR platelet nadir <10 Timing of platelet count fall Clear onset between days 5–10 OR platelet fall ≤1 day Prior heparin exposure within 30 days Consistent with days 5–10 fall, but not clear; onset after day 10 OR fall ≤1 day prior heparin exposure 30–100 days ago Platelet count fall <4 days without recent exposure: Thrombosis or other sequelae Progressive OR recurrent thrombosis; non-necrotizing skin lesions; suspected thrombosis Not proven None: New thrombosis OR skin necrosis; acute systemic reaction post-IV heparin bolus: Other causes for thrombocytopenia None apparent: Possible: Definite: Calculate Loading… RESULTS 0 Points
