title: Testing for Passovoy defect in children with prolonged activated partial thromboplastin time (APTT)
abstract: OBJECTIVE
  To investigate the value of testing for Passovoy defect using the commercially available Passovoy trait plasma (PTP) in children with prolonged activated partial thromboplastin time (APTT).
  
  
  METHODS
  We studied 13 children with prolonged APTT that corrected in a 1:1 mix with normal human plasma but not with PTP. In most children, a thorough laboratory investigation of the intrinsic pathway factors and von Willebrand factor was performed.
  
  
  RESULTS
  Five patients had bleeding manifestations and eight were asymptomatic. Measurement of von Willebrand factor and intrinsic pathway factors revealed abnormal values in eight patients (low von Willebrand activity in six patients, low factor XII in one patient, and the presence of lupus anticoagulant in one patient).
  
  
  CONCLUSIONS
  Our data suggest inability to diagnose Passovoy defect based on a mixing study. This study also raises the question of whether Passovoy defect exists as a distinct coagulation disorder.
authors.affiliation: Department of Pediatrics, Loyola University Medical Center, Maywood, Illinois, USA.
authors.forename: A
authors.initials: A
authors.lastname: Hayani
authors.forename: C R
authors.initials: CR
authors.lastname: Suarez
authors.forename: J E
authors.initials: JE
authors.lastname: Godwin
authors.forename: C
authors.initials: C
authors.lastname: Blakemore
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005169:Factor VIII / Q000032:analysis; D005260:Female; D006470:Hemorrhage / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D008297:Male; D010314:Partial Thromboplastin Time; D012016:Reference Values; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D014841:von Willebrand Factor; D005169:Factor VIII