The influence of iron deficiency on erythrocyte deformability.

The influence of iron deficiency on erythrocyte deformability is controversial. The present study was designed to analyse cell deformability in 14 patients with iron deficiency and controls in a comprehensive way by three different methods, namely erythrocyte filtration, erythrocyte elongation, and measurement of membrane elasticity. Suspensions of washed erythrocytes (haematocrit 0.10) free of leucocytes were used. Erythrocyte deformability measured by filtration was increased by iron deficiency: The relative filtration resistance of a cell in a 3 microns pore was 26.5 +/- 6.9 and 75.8 +/- 23.8 in iron deficiency and controls, respectively (P less than 0.0001). In 5 microns pores the values were 2.80 +/- 1.23 and 3.46 +/- 0.51 (not significant); when the red cell number/volume was adjusted to that in control samples, the value for iron deficiency became significantly lower than in controls (2.32 +/- 0.60, P less than 0.0001). Erythrocyte elongation by centrifugation was unaffected (ratio length/width 1.66 +/- 0.11 and 1.60 +/- 0.10 in iron deficiency and controls, respectively). Membrane elasticity, as assessed by a filter aspiration technique, was also unchanged (membrane elastic modulus 3.94 +/- 0.31 and 3.94 +/- 0.37 x 10(-3) dyn/cm, respectively). It is concluded that iron deficiency does not affect erythrocyte membrane elasticity and that the deformability of whole cells is not impaired, but improved under certain conditions such as the passage of 3 microns pores because of microcytosis with preserved surface/volume ratio. These results are in contrast to earlier studies and they have pathophysiological and clinical implications.