Hematology Consultation along with the 4 T's Clinical Scoring System Improves the Evaluation and Management of Heparin Induced Thrombocytopenia.

Background. Heparin-induced thrombocytopenia (HIT) is a clinicopathologic diagnosis requiring thrombocytopenia, a thrombotic or other heparin-related toxicity and demonstration of heparin-PF4 antibodies. A recently described clinical scoring system to determine the pre-test probability of HIT, the 4 T's, appears promising in evaluation of suspected HIT when based on serotonin release assay (ASH 2003, #1963). We sought to evaluate this scoring system in conjunction with the heparin-PF4 ELISA, which is more widely available. Furthermore, we sought to determine if optical density (OD), as a correlate of heparin-PF4 antibody levels, may have clinical significance.