title: The clinical diagnosis of heparin-induced thrombocytopenia in patients receiving continuous renal replacement therapy.
abstract: BACKGROUND
  Thrombocytopenia is common in critically ill patients who receive continuous renal replacement therapy. Often, these patients receive heparin therapy and the diagnosis of heparin induced thrombocytopenia (HIT) is considered as a potential etiology. No data regarding the clinical diagnosis of HIT is available for patients receiving continuous renal replacement therapy.
  
  
  METHODS
  We performed a retrospective study of 29 consecutive patients who received CRRT in a medical-surgical intensive care unit (ICU) and determined trends in platelet counts following CRRT and the frequency of meeting platelet based clinical criteria for consideration of a HIT diagnosis.
  
  
  RESULTS
  For patient exposures to CRRT concurrent with heparin, 54% met at least one clinical threshold for consideration of the diagnosis of HIT. In 31% of exposures, both a platelet count <100,000/mm3 and a >50% decrease from baseline were seen. In contrast, the majority (73-85%) of patients receiving CRRT had a low pre-test probability of HIT using the "4T's" scoring system. Mean platelet counts while on CRRT concurrent with heparin were significantly lower than when patients received heparin alone (P < 0.02).
  
  
  CONCLUSIONS
  The clinical diagnosis of HIT in ICU patients initiating CRRT is challenging given the decrease in platelet counts seen following CRRT initiation in the majority of patients. A prospective study in this population is needed to optimize patient outcomes.
authors.affiliation: Department of Medicine, Division of Hematology & Oncology, University of Vermont College of Medicine, Burlington, VT 05401, USA. ceholmes@uvm.edu
authors.forename: Chris E
authors.initials: CE
authors.lastname: Holmes
authors.forename: Joe C
authors.initials: JC
authors.lastname: Huang
authors.forename: Carina
authors.initials: C
authors.lastname: Cartelli
authors.forename: Alan
authors.initials: A
authors.lastname: Howard
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Rimmer
authors.forename: Mary
authors.initials: M
authors.lastname: Cushman
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count / Q000379:methods; D017582:Renal Replacement Therapy / Q000009:adverse effects; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis*
chemical_list: D006493:Heparin