The relation between blood viscosity and plasma viscosity in the nephrotic syndrome

Abstract

In order to obtain insight into the relation between blood viscosity and plasma viscosity, we measured these two parameters in 18 Nephrotic Syndrome patients (NS) and in 17 controls. We also measured red cell deformability (ektacytometry) and plasma protein concentrations. The plasma protein composition showed the abnormalities commonly observed in NS: reduced total protein (TP), reduced albumin (Alb) and increased fibrinogen levels. In NS we found significant correlations between plasma viscosity and fibrinogen and between plasma viscosity and the TP minus Alb fraction. In this study, there was no difference in the mean values for the hemorheological parameters between patients and controls. However, the ranges in plasma viscosity and blood viscosity were considerably larger in NS than in the controls. These large ranges made this group of patients a suitable one in which to study the relation between blood viscosity and plasma viscosity. In NS we found that blood viscosity was not proportional to plasma viscosity, although this is normally assumed to be the case. An important consequence of this finding is that relative viscosity, which is assumed to reflect red cell deformability only, is also influenced by plasma viscosity. The dependence of relative viscosity on plasma viscosity means that this parameter needs to be reinterpreted.