Abstract
Platelet dysfunction observed in introductory hemodialysis (HD) patients with chronic renal failure, such as bleeding and decreased platelet aggregation, is improved by HD, and these abnormalities are not seen in maintenance HD patients. However, in HD patients, platelets are thought to be somewhat affected by extracorporeal circulation and uremic toxins, although this is not detected clinically. In this study, platelet dysfunction in maintenance HD patients was evaluated by platelet enzyme activity. Thirty-four healthy volunteers, 30 maintenance HD patients and 21 CAPD patients were selected for this study. Platelet aggregation (collagen 2μg/ml), Mg++-ATPase activity, K+ -EDTA ATPase activity and platelet cyclo-oxygenase (PCO) activity using the platelet malondialdehyde (MDA) production rate were measured, and the following results were obtained: 1) Platelet aggregation was not different among the three groups. 2) Mg++-ATPase activity was 7.0±1.3, 5.7±1.5 and 6.2±1.7nmol Pi/mg protein/min in the healthy subjects, HD patients and CAPD patients, respectively. It was significantly lower in the HD and CAPD patients compared with the healthy subjects (HD: p<0.005, CAPD: p<0.05) but was not different between the two patient groups. 3) The MDA production rate was 13.3±2.0, 8.3±2.0 and 9.6±1.2nmol/109 platelets in the healthy subjects, HD patients and CAPD patients, respectively, and was significantly lower in the two patient groups compared with the healthy subjects (HD: p<0.001, CAPD: p<0.001). Moreover, it was significantly lower in the HD patients compared with the CAPD patients (p<0.05). 4) K+-EDTA ATPase activity was lower than Mg++-ATPase activity, and the three groups could not be compared. These results indicated that platelet dysfunction is improved by blood purification but is still present even in maintenance dialysis patients, though it is not observed clinically. Furthermore, it was found that platelets are less affected by CAPD compared with HD.
