HIT 4T score is a rating used to help clinicians
Evaluation of pretest clinical score (4 T’s) for the diagnosis of heparin-induced thrombocytopenia in two clinical settingsG K Lo , D Juhl, T E Warkentin, C S Sigouin, P Eichler, A Greinacher
Heparin-induced thrombocytopenia (HIT)
It is a side effect of heparin treatment that causes thrombocytopenia (low platelet count). HIT may be classified into two parts. In most cases, type 1 HIT manifests itself during the first 2 days after being exposed to heparin, and the platelet count returns to normal with continuous heparin treatment. Type 1 HIT is a non-immune disease that develops as a consequence of the direct impact of heparin on the activation of platelet cells.
A type 2 HIT is an immune-mediated disease that usually manifests itself 4-10 days after exposure to heparin and is associated with life- and limb-threatening thrombotic events. Type 2 HIT is more common in women than in men. When the word HIT is used in normal medical practice, it refers to type 2 HIT.