Heparin induced thrombocytopenia and re-thrombosis associated with warfarin and fondaparinux in a child

Abstract

An 11-year-old female developed heparin induced thrombocytopenia (HIT) with thrombosis during therapy for lower extremity deep vein thrombosis and pulmonary embolism. Transition from bivalirudin, a direct thrombin inhibitor (DTI), to warfarin resulted in extensive re-thrombosis, and fondaparinux therapy similarly failed. She was then treated with argatroban, and transitioned successfully to warfarin after 9 weeks. The risk of re-thrombosis was ultimately reduced by allowing time for the thrombogenic potential to abate. The argatroban/warfarin transition was monitored with chromogenic factor X levels. This case highlights several difficult problems in pediatric thrombosis.

Figure 1

Course of the patient’s platelet count, thrombotic events, anti-heparin:PF4 antibody titer (HIT Ab titer), and therapy. tPA, tissue plasminogen activator; B, bivalirudin; A, argatroban; H, heparin/low molecular weight heparin; W, warfarin; F, fondaparinux; NEG, negative.

Figure 2

Changes in protein C activity (PC), chromogenic factor X level (FX), prothrombin fragment 1.2 (F1.2), INR, and warfarin dose changes during the transition from argatroban to warfarin. D-dimer is not shown but started at 0.81 FEU/mL (normal <0.36) and consistently decreased to 0.28 FEU/mL (normal <0.45) over this time period.