Erythrocyte deformability evaluated by laser diffractometry in polycythemia vera.

We evaluated the erythrocyte deformability in a group of subjects with polycythemia vera (PV) using a Rheodyn-SSD Laser Diffractometer, at the shear stresses of 6, 12, 30 and 60 Pa. Our data showed a significant decrease of red cell deformability, expressed as elongation index (EI), in PV subjects compared with normal controls. These results suggest that the hyperviscosity syndrome accompanying this myeloproliferative disease may be considered a mixed form, resulting from the association of a polycythemic condition with a sclerocythemic disorder.