title: Validation of the minimal citrate tube fill volume for routine coagulation tests on ACL TOP 500 CTS®.
abstract: BACKGROUND
  CLSI recommends a minimal citrate tube fill volume of 90%. A validation protocol with clinical and analytical components was set up to determine the tube fill threshold for international normalized ratio of prothrombin time (PT-INR), activated partial thromboplastin time (aPTT) and fibrinogen.
  
  
  METHODS
  Citrated coagulation samples from 16 healthy donors and eight patients receiving vitamin K antagonists (VKA) were evaluated. Eighty-nine tubes were filled to varying volumes of >50%. Coagulation tests were performed on ACL TOP 500 CTS(®) . Receiver Operating Characteristic (ROC) plot, with Total error (TE) and critical difference (CD) as possible acceptance criteria, was used to determine the fill threshold.
  
  
  RESULTS
  Receiving Operating Characteristic was the most accurate with CD for PT-INR and TE for aPTT resulting in thresholds of 63% for PT and 80% for aPTT. By adapted ROC, based on threshold setting at a point of 100% sensitivity at a maximum specificity, CD was best for PT and TE for aPTT resulting in thresholds of 73% for PT and 90% for aPTT. For fibrinogen, the method was only valid with the TE criterion at a 63% fill volume.
  
  
  CONCLUSIONS
  In our study, we validated the minimal citrate tube fill volumes of 73%, 90% and 63% for PT-INR, aPTT and fibrinogen, respectively.
authors.affiliation: Clinical Laboratory, Department of Hematology, GZA Hospitals, Antwerp, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Ver Elst
authors.forename: S
authors.initials: S
authors.lastname: Vermeiren
authors.forename: S
authors.initials: S
authors.lastname: Schouwers
authors.forename: V
authors.initials: V
authors.lastname: Callebaut
authors.forename: W
authors.initials: W
authors.lastname: Thomson
authors.forename: S
authors.initials: S
authors.lastname: Weekx
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D001780:Blood Coagulation Tests / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D001800:Blood Specimen Collection / Q000379:methods*; D006801:Humans; D019934:International Normalized Ratio; D010314:Partial Thromboplastin Time / Q000295:instrumentation / Q000379:methods; D011517:Prothrombin Time / Q000295:instrumentation / Q000379:methods; D012372:ROC Curve; D015203:Reproducibility of Results
chemical_list: D000925:Anticoagulants
keywords: ACL TOP 500; Citrate tube; coagulation; fill volume