Red cell deformability, splenic function and anaemia in thalassaemia

Red cell deformability (RCD) was measured in 38 patients with alpha-thalassaemia and 48 patients with beta-thalassaemia, of whom 13 had undergone splenectomy. All splenectomized patients, but none of those with intact spleens, had very rigid erythrocytes with an elongation index <0.45 at a high shear stress of 30 Pa suggesting a splenic recognition threshold for removal of rigid red cells. At this shear stress RCD correlated strongly with the degree of anaemia in both the splenectomized (r = 0.81, P < 0.001) and non-splenectomized beta-thalassaemic patients (all patients r = 0.81, P < 0.001; homozygous beta-thalassaemic patients r = 0.51, P = 0. 01). These data suggest that reduced RCD is a major determinant of anaemia in thalassaemia.