Second, patients with thrombocytopenia, persisting for at least 24 hours postoperatively, a 4 T score >3 indicating at least an intermediate risk for HIT or a positive PF4/heparin immunoglobulin G (IgG) ELISA, should receive alternative anticoagulation, despite other potential causes for thrombocytopenia. This evidence concerns the gene PF4 and Thrombocytopenia.