Blood viscosity studies in native and reconstituted polycythemic blood

In twelve subjects with Polycythemia vera (P.V.) whole blood, plasma and relative viscosities and the main factors capable of influencing such parameters (Hct, RBCs, WBCs and platelet count, total proteins, gamma-globulins and fibrinogen) were investigated. Ten normal subjects of similar age and sex were studied as control. Whole blood viscosity was determined both in basal conditions and after reconstitution of Hct to normal values by adding some autologous plasma. After the reconstitution of Hct the subjects studied were divided into two groups on the basis of the correlation between Hct and whole blood viscosity. The first group (group A) had a good correlation between Hct and whole blood viscosity; on the other hand the second group (group B) did not show any significant correlation between these two parameters after reconstitution. In basal conditions none of the parameters capable of influencing whole blood viscosity or plasma viscosity permitted any discrimination between the two groups. The relative viscosity, which represents an indirect index of red blood cell deformability, appears to be more elevated in group B. Therefore, the different behaviour of polycythemic blood after reconstitution of Hct might be conceived to be due to a difference in red cell deformability.