ACQUIRED INHIBITORS TO FACTOR-V AND FACTOR-X AFTER EXPOSURE TO TOPICAL THROMBIN - INTERFERENCE WITH MONITORING OF LOW-MOLECULAR-WEIGHT HEPARIN AND WARFARIN

Repeated surgical exposure to topical bovine thrombin is known to be a ssociated with the development of antibodies to bovine and human throm bin and factor V. This is demonstrated by abnormalities of in vitro co agulation assays and, rarely, postoperative bleeding. We describe a 4- year-old child in whom an antibody to bovine factor X developed after cardiac surgery; this antibody interfered with the heparin anti-Xa ass ay, thereby complicating the monitoring of heparin therapy.