title: Contributions of biological tests and the 4 Ts score in the diagnosis of heparin induced thrombocytopenia.
abstract: BACKGROUND
  Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction caused by antibodies to the heparin/platelet factor 4 (PF4) complexes. HIT diagnosis is challenging and depends on clinical presentation and laboratory tests. We investigated the interest of the combined use of 4 Ts score and the functional and immunological tests for the diagnosis of HIT.
  
  
  METHODS
  We analyzed 178 patients with suspected HIT, for which the 4 Ts score was calculated. Heparin-PF4 antibodies were detected by both Heparin-induced platelet activation test (HIPA) and Heparin platelet induced antibodies enzyme immunoassay.
  
  
  RESULTS
  Our results shown that in low probability group, 85% of plasmas were found negative versus 55.5% in the high probability group. On the other hand, 22.2% of patients were HIT positive in high probability group versus 0% in the low probability group.
  
  
  CONCLUSIONS
  These results confirmed that the negative predictive value of the HIT score was high. The 4T's model has demonstrated excellent sensitivity but its specificity was limited. The specificity of the functional and immunological test is high only in a context suggestive of HIT. Both methods should be considered complementary in the diagnostic strategy.
authors: Laboratory of hematology, Faculty of Medicine, Cadi Ayyad University, University Hospital, Marrakech, Morocco.
authors: Khalil
authors: K
authors: Haouach
authors: Brahim
authors: B
authors: Admou
authors: Pascal
authors: P
authors: Lauriant
authors: Laila
authors: L
authors: Chabaa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000276:immunology*; D011446:Prospective Studies; D012107:Research Design; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis* / Q000276:immunology; D055815:Young Adult
chemical_list: D000906:Antibodies; D010978:Platelet Factor 4; D006493:Heparin
keywords: 4 Ts scoring system; Heparin-induced thrombocytopenia; antibodies