title: Optical density values correlate with the clinical probability of heparin induced thrombocytopenia.
abstract: BACKGROUND
  Heparin induced thrombocytopenia is a clinicopathologic syndrome that may result in severe thrombotic sequelae without prompt diagnosis and treatment. A clinical scoring system to assess the pre-test probability of heparin-induced thrombocytopenia, the 4 T's, has been reported to correlate with the serotonin release assay.
  
  
  METHODS
  We performed a single-center, retrospective study correlating the 4 T's score with the commercial heparin-PF4 ELISA.
  
  
  RESULTS
  One hundred forty four cases were identified. The pre-test probability scores were: low probability 45.8%, moderate probability 41.0% and high probability 13.2%. The median optical density was 0.148, 0.223 and 0.470 for low probability, moderate probability and high probability, respectively (P < 0.0005). The frequencies of obtaining an optical density>1.00 for these probability scores were 1.5%, 6.8%, and 36.8%, respectively (P < 0.0005).
  
  
  CONCLUSIONS
  Heparin-PF4 ELISA optical density values increase with increasing probability of heparin induced thrombocytopenia.
authors.affiliation: Hematology-Oncology Service, Department of Medicine, Walter Reed Army Medical Center, 6900 Georgia Ave, NW, Washington, DC 20307, USA. brendan.weiss@us.army.mil
authors.forename: Brendan M
authors.initials: BM
authors.lastname: Weiss
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Shumway
authors.forename: Robin S
authors.initials: RS
authors.lastname: Howard
authors.forename: Lloyd K
authors.initials: LK
authors.lastname: Ketchum
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Reid
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D010978:Platelet Factor 4 / Q000097:blood*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis*
chemical_list: D010978:Platelet Factor 4; D006493:Heparin