The Significance of Changes of Viscosity in Pathological Sera

Measurements of the viscosity of blood serum reported by clinical observers have in many cases shown results that are seemingly paradoxical, as for example a small effect of high dilution on serum viscosity in nephrosis; a low serum viscosity in pernicious anemia, and a high one in icterus, though they are both characterized by a high bilirubin content of the blood; a low serum viscosity in many cases of nephritis and uremia; a very high one in cases of cyanosis. We have attempted to reproduce some of these pathological states in order to investigate the physicochemical basis of these empirical relationships. The investigations of Loeb (1) on proteins have shown that the measurement of viscosity is an excellent means of demonstrating delicate changes in the physicochemical structure of systems containing large molecules in solution. In blood serum we have a system containing hydrophil colloids which responds to extremely small disturbances in the environment by easily measurable changes in the viscosity. The viscosity was measured by the time of outflow through a Poiseuille viscosimeter. 10 cc. of blood serum were used and the temperature kept constant within 0.01’ at 37.5’ in a Freas thermostat. The quotient of the time of outilow of the serum over the time of outflow of pure water through the same viscosimeter at the same temperature was taken as the relative viscosity of the protein solution. Blood serum, as can be seen from the viscosity at different dilutions (Table I) shows a remarkable ability to keep its viscosity constant in spite of dilution. If we compare the effects of dilution on the viscosity of such a