HIT 4T's score

Diagnose heparin-induced thrombocytopenia.

The global unit selector only affects unanswered questions
1.Thrombocytopenia - Platelet count fall:
2.Thrombocytopenia - Platelet nadir:
3.Timing of platelet count fall - Documented onset on which day relative to heparin exposure?
4.Number of days since recent PRIOR heparin exposure?
6.Skin necrosis?
7.Non-necrotizing skin lesions?
8.Acute systemic reaction postintravenous unfractionated heparin?
9.Other cause for Thrombocytopenia? (At physician's discretion)
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1. Thrombocytopenia - Platelet count fall:

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About this Calculator

The ‘4 T’s’ (thrombocytopenia, timing of platelet count fall, thrombosis or other sequelae, and other causes for thrombocytopenia,) enable the calculation of a pretest clinical score for the diagnosis of heparin-induced thrombocytopenia. In one series, a low pretest clinical score for HIT was associated with a high-negative predictive value. Although a low score might be suitable for ruling out HIT in some clinical settings, this approach has not yet been validated prospectively.


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