Thromboxane B2 blood levels and incipient system clotting in heparin free hemodialysis.

Clotting of the extracorporal system is the main complication of heparin free hemodialysis performed in patients with an increased risk of bleeding. The authors compared thromboxane B2, platelet factor 4, beta-thromboglobulin, and thromboelastography in systemic blood as markers of thrombogenicity during hemodialysis in eight patients with an increased risk of bleeding. Measurements were performed during hemodialysis with and without heparin. Thromboxane B2 levels in centrifuged blood were evaluated by an 125I assay system using a special extraction with mini-columns and magnetic separation (normal 32-64 pg/ml). At the onset of hemodialysis, thromboxane B2 concentrations in the inflow arterial blood line were lower than normal (30 +/- 23 pg/ml). Thromboxane B2 increased (97 +/- 105 versus 40 +/- 26 pg/ml) and was significantly higher during heparin free hemodialysis than during hemodialysis with heparin (p = 0.01, Wilcoxon matched pairs signed rank test). The highest values were observed in 5 cases with signs of clotting (152 +/- 122 pg/ml). Among the investigated parameters, thromboxane B2 proved to be the most significant serum parameter correlated with platelet activation and the consequently increased risk of incipient clotting during heparin free hemodialysis.