LAUSR

Patients with end-stage renal disease (ESRD) receiving hemodialysis (HD) often experience bleeding. However, mechanisms behind this bleeding tendency are incompletely understood but may involve platelet dysfunction. We, therefore, studied platelet-dependent thrombus formation in flowing whole blood inside a microchip coated with collagen, and its association with circulating von Willebrand factor (VWF). Blood samples were obtained in 22 patients before and after HD. The area under the 10 min flow pressure curve in a microchip (AUC10) reflecting total platelet thrombogenicity was measured, using the Total Thrombus-formation Analysis System (T-TAS01). AUC10 < 260 indicates platelet dysfunction. VWF activity and antigen in plasma were also assayed. VWF levels were moderately elevated and increased further after HD (P < 0.01 or lower). In contrast, AUC10 before and after HD was < 260 in 17/22 patients and < 130 in 15/22 patients, with no statistically significant difference in pre- vs post-HD measurements, indicating reduced platelet thrombogenicity, but with some variability as 5/22 patients showed normal platelet responsiveness. AUC10 and VWF activity or antigen levels in plasma were not correlated, either before or after HD. Most ESRD patients display moderate-to-severe platelet dysfunction as assessed by shear-induced platelet-dependent thrombus formation with T-TAS01. HD does not influence platelet function despite HD-induced elevations in VWF. T-TAS01 should be further evaluated as a tool in the assessment of bleeding risk in patients on HD.