Shear stress-induced platelet aggregation in children with minimal change nephrotic syndrome

Abstract

Analysis of the hemostasis system using biochemical techniques in children with minimal change nephrotic syndrome (MCNS) has previously been restricted to in vitro assays. The recent introduction of measurement of shear stress-induced platelet aggregation (SIPA) using platelet-rich plasma (PRP) has facilitated detailed investigation of the hemostatic system in vivo. In order to further analyze the etiology of the thrombotic tendency exhibited by patients with childhood MCNS, we investigated SIPA at both low shear stress (L-SIPA) and high shear stress (H-SIPA) in 14 children with MCNS using PRP collected weekly after commencing prednisolone therapy. Seven patients were newly diagnosed cases of MCNS (ND) whereas the remainder had suffered a disease relapse (DR). Prior to prednisolone therapy L-SIPA, which was thought to be affected by fibrinogen (Fbg) levels, was significantly increased in both patient groups compared to normal controls (17.4 +/- 4.1% vs. 3.6 +/- 0.7%, ND vs control, p < 0.01: 11.7 +/- 3% vs. 2 +/- 0.7%, DR vs control, p < 0.01) with values declining at weekly intervals thereafter. Plasma Fbg levels in simultaneously collected samples followed a similar course. In contrast, H-SIPA, which was thought to be affected by von Willebrand factor (VWF), was significantly enhanced in MCNS patients after 1 week of prednisolone therapy compared to the controls (45 +/- 5.1% vs. 26.3 +/- 3.5%, ND vs normal, p < 0.05: 36.9 +/- 3.3% vs. 25.5 +/- 1.6%, DR vs. normal, p < 0.05). Plasma ristocetin cofactor and VWF antigen levels in simultaneously collected samples followed a similar course, whereas thrombin-antithrombin complex (TAT) levels remained constant. These results indicate that SIPA is enhanced in the acute stage of childhood MCNS, especially L-SIPA prior to the initiation of prednisolone therapy and H-SIPA after 1 week of prednisolone therapy, and that these phenomena may be affected by plasma Fbg and VWF levels, respectively. The enhanced SIPA may play an important thrombogenic role in the acute phase of childhood MCNS.