ヘパリン依存性血板減少症により血液透析回路内に凝固を来した1症例

Thrombocytopenia induced by heparin administration, although rare, is of great importance in clinical medicine, since thromboembolism or disseminated intravascular coagulation as a result of heparin therapy has been reported in the literature.<br>Recently, we experienced a patient with chronic renal failure on dialysis who manifested blood coagulation in the hemodialyzer and persistence of thrombocytopenia when heparinizing dialysis units were used.<br>The patient was a 78-year-old man with end-stage kidney who was treated by hemodialysis with heparin on and after the day of admission to the hospital. However, on the 11th occasion of dialysis, remarkable blood coagulation in the dialyzer occurred with thrombocytopenia (platelets<10×10⁴/mm³). This pathologic process occurred upon every occasion of dialysis after the 11th time. We therefore increased the dose of heparin, administered ticlopidin orally, and switched the dialyzer to a different type employing another type of membrane. However, none of these manipulations stopped the coagulation or prevented thrombocytopenia. Laboratory examination disclosed hyperactivity of β-TG and PF 4 with associated thrombocytopenia during hemodialysis. Therfore, we tried aspirin instead of ticlopidin, to prevent the coagulation process by suppressing these factors. The administration of aspirin corrected the elevation of β-TG and PF 4 and thrombocytopenia, resulting in relief of blood coagulation.<br>Also, we were able to find by in vitro study that the enhancement of platelet aggregation was induced by the addition of heparin to a mixture of normal platelet-rich plasma and the patient's platelet-poor plasma. These data suggested that heparin, which usually acts as an anti-coagulant during hemodialysis, induced platelet aggregation and blood coagulation in the dialyzers in this case. Furthermore, aspirin was effective for inhibiting the heparin-induced platelet aggregation.