PF4 and Thrombocytopenia: A pre-test clinical score (including thrombocytopenia, timing of platelet count fall, thrombosis, presence of other causes for thrombocytopenia, the so-called 4 T's) has been developed to establish the clinical suspicion of HIT [10], while heparin-platelet factor 4-immunoglobulin G (IgG) (PF4-IgG) antibodies and 14C-serotonin release assay are useful diagnostic tests [2].