A comparison of the erythrocyte sedimentation rate and plasma viscosity in detecting changes in plasma proteins.

The Westergren erythrocyte sedimentation rate (ESR) and plasma viscosity were compared in 114 patients and their correlations with total and differential plasma protein fractions were analysed. There is a linear correlation between these two screening tests. Higher correlation coefficients were obtained between the plasma viscosity and fibrinogen and alpha and gamma globulins than with the ESR. Albumin affected the two tests in opposite directions. The ESR was falsely increased by a fall in haemoglobulin even within two standard deviations from the mean. Both tests gave an appreciable number of incorrect values--the plasma viscosity in 21 cases and the ESR in 33. The cause for these is discussed. It is concluded that the plasma viscosity is the more sensitive and reliable measure of changes in acute phase protein reactants and more useful for monitoring clinical progress.