4 Ts | 2 points | 1 point | 0 points |
---|---|---|---|
Thrombocytopenia | Platelet count >50% and platelet nadir = 20* | Platelet count decrease 30% to 50% or platelet nadir 10 to 19 | Platelet count decrease < 30% or platelet nadir < 10 |
Timing of platelet count decrease | Clear onset between days 5 and 10 or decrease = 1 day (prior heparin exposure within 30 days) | Consistent with decrease between days 5 and 10, but not clear (for example, missing platelet counts); onset after day 10; or decrease = 1 day (prior heparin exposure 30 to 100 days before) | Platelet count decrease < 4 days without recent exposure |
Thrombosis or other sequelae | New thrombosis (confirmed); skin necrosis; acute systemic reaction after intravenous unfractionated heparin bolus | Progressive or recurrent thrombosis; non-necrotizing (erythematous) skin lesions; suspected thrombosis (not proven)** | None |
Other causes for thrombocytopenia | None apparent | Possible++ | Definite++ |