ON WHOLE-BLOOD VISCOSITY MEASUREMENTS IN HEALTHY-INDIVIDUALS AND IN RHEUMATOID-ARTHRITIS PATIENTS

Different methods of measuring whole blood viscosity using a couette r otational viscometer were compared to establish its use in clinical rh eumatological practice. The relationship between blood viscosity and h ematocrit was approximately exponential and no significant differences in the slopes were found between healthy controls and rheumatoid arth ritis patients. Correction of native blood viscosity to a standard hem atocrit of 40% by extrapolation from a standard regression curve, esta blished by concentration/dilution of samples from healthy persons to c orrect for hematocrit differences and at sh;ear rate 92s(-1) was the b est method for differentiating between viscosities of patients and con trols. It was also the least laborious method, requiring the smallest amounts of blood and having the lowest method error. Native blood visc osity, corrected blood viscosity, plasma viscosity and red cell aggreg ation were all significantly higher and hematocrit significantly lower in rheumatoid arthritis patients than in controls.