Comparison between whole blood viscosity measured and calculated in subjects with monoclonal gammopathy of undetermined significance and in patients with multiple myeloma: Re-evaluation of our survey

BACKGROUND: in this study, with a re-evaluation of the hemorheological determinants previously described in MGUS subjects and in MM patients, we have detected the calculated whole blood viscosity, according whether to the hematocrit and total plasma protein concentration (de Simone formula) or to the haematocrit and plasma fibrinogen level (Merrill formula), and a marker of the erythrocyte aggregation (albumin/fibrinogen level).METHODS: data were expressed as means +/- standard deviation. Student's t test for unpaired data was used to compare MGUS subjects and MM patients. The correlation coefficient between mean erythrocyte aggregation (MEA) and hematocrit (Ht) was evaluated in MGUS, MM and MGUS + MM groups using the Spearman test.RESULTS: the comparison between MGUS and MM shows that the measured blood viscosity and calculated blood viscosity based on hematocrit and total plasma protein, but not which estimated in relation to the hematocrit and plasma fibrinogen, differentiate the two groups. A difference between the two groups also regards the measured erythrocyte aggregation and its surrogate marker. In addition, the measured plasma viscosity at low shear rate (0.51 s(-1)) and, in particular, the ratio between plasma viscosity at low (0.51 s(-1)) and high (450 s(-1)) shear rates distinguish MGUS and MM.CONCLUSIONS: calculated blood viscosity (de Simone formula and other formulas) and the surrogate marker of erythrocyte aggregation disclose an alike trend with the corresponding hemorheological determinants obtained by using their direct measurement.