Uremic patients have two opposite features in hemostatic status, that is, bleeding and thrombophilic tendency. Platelet functions for normal hemostasis are impaired, possibly contributing to the bleeding tendency in uremic patients. In contrast, platelet hyperaggregability and hypercoagulability that are commonly observed in uremic patients may be associated with their high incidence of thrombotic diseases. Recent studies suggested that platelet microparticles (PMPs) which are small vesicles with procoagulant activity released from the activated platelets might be relevant to thrombogenesis. This research investigated this hemostatic paradox in uremia by analyzing the characteristics of PMPs in circulation.
The subjects were patients under hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD), and healthy controls. The PMPs analysis was performed using a flow cytometer. The procoagulant and adhesive activities of PMPs were specially determined by their expressions of Annexin V and P-selectin, respectively. The influence of HD procedure and arterio-venous (A-V) fistula on PMP formation were also assessed. The counts of total PMPs and PMPs with procoagulant and adhesive activities were statistically greater in both uremic groups, but those PMP counts did not differ between the uremic groups. The HD procedure and A-V fistula did not affect the PMP formation. In conclusion, the elevated PMP counts may be responsible for the thrombotic tendency in uremia despite impaired platelet function.