title: Thrombophilia testing in children: a 7 year experience.
abstract: BACKGROUND
  Incidence of venous thromboembolism (VTE) in children is reported to be increasing. We examined thrombophilia testing results in children with VTE that presented in inpatient and outpatient settings to explore patterns of thrombophilia testing.
  
  
  METHODS
  
  
  
  METHODS
  Children, ages 0-20 years with VTE seen at our institution from Jan 2005 to Apr 2012 were studied retrospectively. All patients with VTE confirmed by imaging were eligible and the presence of significant risk factors was evaluated. Thrombophilia was diagnosed if >1 tests confirmed: persistently low protein C (PC), protein S (PS), and antithrombin (AT) following VTE resolution, persistent antiphospholipid antibodies (APA) positivity >12 weeks from first test, factor V Leiden (FVL) and prothrombin mutation (PTm) hetero- or homozygosity, elevated plasminogen activator inhibitor (PAI-1) levels with 4G/5G or 4G/4G polymorphisms, methylene tetrahydrofolate reductase (MTHFR) polymorphisms with elevated fasting homocysteine levels.
  
  
  RESULTS
  Three hundred ninety-two patients met inclusion criteria. At least one test was ordered in 157/239 inpatients. All 153 outpatients had >1 test ordered. Thrombophilia rate differences between inpatients and outpatients did not reach statistical significance except for PC deficiency, which was significantly higher in outpatients. Of inpatients, central venous line (CVL) was significantly associated with not having tests done (P < 0.0022).
  
  
  CONCLUSIONS
  This study of pediatric VTE demonstrated a low thrombophilia rate in both inpatient and outpatient populations. The role of testing in other pediatric patients should be further explored.
authors.affiliation: Department of Pediatrics, Riley Hospital for Children at Indiana University Health, Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: A
authors.initials: A
authors.lastname: Mahajerin
authors.forename: P
authors.initials: P
authors.lastname: Obasaju
authors.forename: G
authors.initials: G
authors.lastname: Eckert
authors.forename: T A
authors.initials: TA
authors.lastname: Vik
authors.forename: R
authors.initials: R
authors.lastname: Mehta
authors.forename: M
authors.initials: M
authors.lastname: Heiny
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D019851:Thrombophilia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D054556:Venous Thromboembolism / Q000097:blood*
keywords: pediatric hematology/oncology; thrombophilia; thrombosis