title: Heparin but not citrate anticoagulation of blood preserves platelet function for prolonged periods.
abstract: BACKGROUND
  Current guidelines state that platelet aggregation studies should be conducted within 4 h of venepuncture because of the decline in sensitivity to platelet agonists. This constrains studies of platelet activity in clinical situations where samples need to be transported or there are unavoidable delays prior to assessment.
  
  
  OBJECTIVE
  The aim of the present study was to compare systematically the responses of platelets stored in the presence of either citrate or heparin, the two most widely used anti-coagulants, using a range of standard techniques.
  
  
  METHODS
  Blood was taken from healthy volunteers and either assessed immediately or stored at ambient temperature (18-25 degrees C) for 24 h. Platelet reactivity to a range of agonists was determined by a combination of 96-well plate techniques; light transmission aggregometry, thrombi adhesion, ATP and ADP release, and TxA(2) release; by whole blood aggregometry; and by PFA-100.
  
  
  CONCLUSIONS
  Testing using 96-well plate techniques allowed for the simultaneous measurement of responses to multiple concentrations of multiple agonists. The responses of platelets from blood anti-coagulated with heparin were predominantly preserved in all assays after 24 h storage, whereas, responses of platelets stored in blood anti-coagulated with citrate were greatly diminished. Consequently, anti-coagulation with heparin, but not citrate, preserves platelet responses for up to 24 h as determined by a range of techniques.
authors.affiliation: Queen Mary University of London, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Truss
authors.forename: P C J
authors.initials: PC
authors.lastname: Armstrong
authors.forename: E
authors.initials: E
authors.lastname: Liverani
authors.forename: I
authors.initials: I
authors.lastname: Vojnovic
authors.forename: T D
authors.initials: TD
authors.lastname: Warner
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D001792:Blood Platelets / Q000502:physiology*; D001793:Blood Preservation / Q000379:methods*; D019343:Citric Acid / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D010979:Platelet Function Tests
chemical_list: D000925:Anticoagulants; D019343:Citric Acid; D006493:Heparin