title: Heparin-induced thrombocytopenia in the critical care setting: diagnosis and management.
abstract: BACKGROUND
  Thrombocytopenia is a common occurrence in critical illness, reported in up to 41% of patients. Systematic evaluation of thrombocytopenia in critical care is essential to accurate identification and management of the cause. Although sepsis and hemodilution are more common etiologies of thrombocytopenia in critical illness, heparin-induced thrombocytopenia (HIT) is one potential etiology that warrants consideration.
  
  
  OBJECTIVE
  This review will summarize the pathogenesis and clinical consequences of HIT, describe the diagnostic process, and review currently available treatment options.
  
  
  METHODS
  MEDLINE/PubMed search of all relevant primary and review articles.
  
  
  CONCLUSIONS
  HIT is a clinicopathologic syndrome characterized by thrombocytopenia (>/=50% from baseline) that typically occurs between days 5 and 14 after initiation of heparin. This temporal profile suggests a possible diagnosis of HIT, which can be supported (or refuted) with a strong positive (or negative) laboratory test for HIT antibodies. When considering the diagnosis of HIT, critical care professionals should monitor platelet counts in patients who are at risk for HIT and carefully evaluate for, a) temporal features of the thrombocytopenia in relation to heparin exposure; b) severity of thrombocytopenia; c) clinical evidence for thrombosis; and d) alternative etiologies of thrombocytopenia. Due to its prothrombotic nature, early recognition of HIT and prompt substitution of heparin with a direct thrombin inhibitor (e.g., argatroban or lepirudin) or the heparinoid danaparoid (where available) reduces the risk of thromboembolic events, some of which may be life-threatening.
authors.affiliation: Acute Care Surgery, Trauma, Burn, Critical Care, Emergency Surgery, Department of Surgery, University of Michigan Health System, Ann Arbor, MI, USA.
authors.forename: Lena M
authors.initials: LM
authors.lastname: Napolitano
authors.forename: Theodore E
authors.initials: TE
authors.lastname: Warkentin
authors.forename: Amjad
authors.initials: A
authors.lastname: Almahameed
authors.forename: Stanley A
authors.initials: SA
authors.lastname: Nasraway
mesh_terms: D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use*; D001120:Arginine / Q000031:analogs & derivatives; D002809:Chondroitin Sulfates / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003422:Critical Care; D003871:Dermatan Sulfate / Q000627:therapeutic use; D006493:Heparin / Q000009:adverse effects*; D006496:Heparinoids / Q000627:therapeutic use; D006497:Heparan Sulfate / Q000627:therapeutic use; D006629:Hirudins; D006801:Humans; D010875:Pipecolic Acids / Q000627:therapeutic use; D010976:Platelet Count; D011994:Recombinant Proteins / Q000627:therapeutic use; D012307:Risk Factors; D013449:Sulfonamides; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000378:metabolism; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D001120:Arginine; D002809:Chondroitin Sulfates; D003871:Dermatan Sulfate; D006493:Heparin; D006496:Heparinoids; D006497:Heparan Sulfate; D006629:Hirudins; D010875:Pipecolic Acids; D011994:Recombinant Proteins; D013449:Sulfonamides; D013917:Thrombin; C035838:danaparoid; C031942:argatroban; C083544:lepirudin