Heparin-resistant Thrombosis Due to Homozygous Antithrombin Deficiency Treated With Rivaroxaban: A Case Report.
Heparin fulfills its anticoagulant action through activation of antithrombin (AT), and thus thrombosis secondary to AT deficiency can be associated with heparin resistance.



A 12-year-old girl with severe venous thrombosis was referred to us because of undetectable anti-Xa levels despite low-molecular-weight heparin therapy. Laboratory investigations revealed a homozygous AT mutation in the heparin binding site (AT Budapest III). She was subsequently treated with rivaroxaban successfully.



Heparin resistance warrants evaluation for AT deficiency. Rivaroxaban may be considered a valid anticoagulant alternative to low-molecular-weight heparin in these patients.
Departments of *Pediatric Hematology Wilhelmina Children's Hospital ‡Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, The Netherlands †Department of Pediatrics, Hospital Gasthuisberg, University Hospital Leuven, Leuven, Belgium.
Lore
L
Van Bruwaene
Albert
A
Huisman
Rolf T
RT
Urbanus
Birgitta
B
Versluys
D000990:Antithrombin III / Q000032:analysis; D020152:Antithrombin III Deficiency / Q000150:complications*; D001665:Binding Sites / Q000235:genetics; D002648:Child; D004351:Drug Resistance / Q000235:genetics; D065427:Factor Xa Inhibitors; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D000069552:Rivaroxaban / Q000008:administration & dosage*; D013927:Thrombosis / Q000188:drug therapy*
D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; C055367:antithrombin III Budapest 2; D000990:Antithrombin III; D000069552:Rivaroxaban