Erythrocyte deformability and hemorheological profile in multiple myeloma.

The hemorheological profile in multiple myeloma (MM) has been extensively studied. Our investigation regarded the behavior of whole-blood viscosity, plasma viscosity and erythrocyte deformability in MM. We enrolled 24 MM patients; 13 of them had been recently diagnosed and were at the initial stage of therapy, 6 were on consolidation/conservation therapy and 5 had achieved a complete remission. On fasting venous blood we evaluated whole-blood and plasma viscosity at high and low shear rates, haematocrit, the ratios between whole-blood viscosity (at high and low shear rate) and haematocrit×100, the ratio between plasma viscosity at low and high shear rate and the erythrocyte deformability examined by using laser diffractometry and expressed as elongation index. A significant increase in plasma viscosity at low shear rate and a marked decrease in haematocrit were observed in MM patients compared with normal controls. Also the ratio between the high shear rate whole-blood viscosity and haematocrit ×100 and the ratio between the low and high shear rate plasma viscosity were significantly increased in MM patients. A significant decrease in erythrocyte deformability, especially at low shear stresses, was found. We discuss some hypotheses that might explain the behavior of red blood cell deformability in MM, considering that its impairment, in addition to the increase of plasma viscosity, can alter the microcirculatory flow in these patients.

Hemorheological parameters in Monoclonal Gammopathy of Undetermined Significance (MGUS).

There is scarcity of information about the hemorheological pattern in subjects with Monoclonal Gammopathy of Undetermined Significance (MGUS). This preliminary research is focused on the behaviour of whole-blood and plasma viscosity, haematocrit and erythrocyte deformability in the above clinical condition. We enrolled 21 MGUS subjects (10 women and 11 men; mean age 66.4 ± 11.6 years). In fasting venous blood we examined whole-blood and plasma viscosity at high and low shear rates, haematocrit, the ratios between whole-blood viscosity (at high and low shear rate) and haematocrit × 100, the ratio between plasma viscosity at low and high shear rate, and the erythrocyte deformability expressed as elongation index. By comparing normal controls to MGUS subjects a significant increase in whole-blood viscosity at high shear rate and in plasma viscosity at low shear rate were observed. In MGUS subjects the ratios between the high and low shear rate blood viscosity and haematocrit × 100, as well as the ratio between the low and high shear rate plasma viscosity were significantly higher. In MGUS subjects a marked decrease in erythrocyte deformability was also observed. The alteration of the hemorheological profile found in these subjects might be involved in the pathogenesis of thromboembolic events, which occur with a high frequency in MGUS.