Background:

There is an increased incidence of venous thromboembolic events (VTE) in pediatrics due to improved diagnosis and survival of children with VTE.

The mortality rate is estimated at 2%.

The most common etiologies vary by age - Central venous catheters in neonates and infants, and inherited thrombophilia in children and adolescents.

Learning Points:

1. With neonates and infants, carefully assess medical history from neonatal period. Umbilical lines? PICC? Broviac? History of these is likely to be the cause.

2. In children and adolescents, unprovoked VTE is most likely due to inherited thrombophilia, and can be DVT, PE, Portal venous thrombus, etc.

   1. Antithrombin deficiency: The first discovered inherited thrombophilia. The result is a lack of inhibition of coagulation factors – IIa, IXa, Xa, XIIa.

   2. Protein C or/and S deficiency: The result is lack of inhibition of activated Factor V.

   3. Factor V Leiden: Most common inherited thrombophilic defect. Resultant activated Factor V is resistant to normal Protein C and S activity.

   4. Prothrombin Mutation: Second most common inherited thrombophilia. The result is increased levels of prothrombin, which increases the half-life of factor Va.

3. Initial treatment of clinically significant VTE can start with enoxaparin (1-1.5 mg/kg q12-24h, while checking Anti-Xa levels 4 hours after administration for therapeutic dosing.)

 

Pearl: Testing for thrombophilia is not always appropriate when diagnosing pediatric patients with their first VTE, but in children and adolescents with first diagnosed, unprovoked VTE, it is worthwhile to send off the initial hypercoaguability work up as this can affect the duration of treatment and need for testing or evaluation. Enoxaparin is a recommended medication to start therapeutic treatment of VTE, even in pediatric patients.

References

Van Ommen CH, Nowak-Gottl U. Inherited Thrombophilia in Pediatric Venous Thromboembolic Disease: Why and Who to Treat. Frontiers in Pediatrics. 2017: 5(20).

The Harriet Lane Handbook, 20th edition. Chapter 29: Drug Dosages. 2015