HIT 4T's score

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.