Heparin-induced thrombocytopenia after liver transplantation.

Backgound. Unfractionated heparin sodium (UFH) or low-molecular weight heparin (LMWH) is used in anticoagulant protocols at several institutions to prevent thrombosis after liver transplantation. Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated reaction to heparin, resulting in platelet count decreases of more than 50%. The frequencies of HIT after liver transplantation and platelet factor 4/heparin-reactive antibody (HIT antibody) positivity in liver transplantation patients, however, are unknown. Patients and Methods. The 32 men and 20 women underwent living donor liver transplantation. We started LMWH (25 IU/kg/h) on postoperative day (POD) 1, switching to UFH (5000 U/d) on POD 2 or 3. The dose of UFH was changed according to the activated clotting time level. HIT antibody levels were measured the day before surgery and on POD 7 and 14. Platelet count was measured daily for 3 weeks. Results. The average platelet counts preoperatively, and on POD 7, 14, and 21 were 65, 88, 149, and 169 X 10(9)/L, respectively. Two patients developed hepatic artery thrombosis on POD 11 and 19, respectively, although they were HIT antibody-negative and their platelet counts were stable. In 2 other patients, the platelet count decreased suddenly from 107 X 10(9)/L on POD 4 to 65 X 10(9)/L on POD 6 and from 76 X 10(9)/L on POD 7 to 33 x 10(9)/L on POD 9, respectively. The heparin-induced platelet aggregation test was negative in these patients. The percentage of HIT antibody-positive patients was 0.5% preoperatively, 5.6% on POD 7, and 5.6% on POD 14. None of the subjects/patients developed UFH-related HIT. Conclusions. In our series, the occurrence of HIT after liver transplantation was uncommon.