Erythropoiesis: Erythrocyte Deformability is Reduced and Fragility increased by Iron Deficiency

Hypochromic and microcytic erythrocytes, resulting from absolute iron deficiency, have a shortened survival due to ineffective production coupled with accelerated reticuloendothelial cell sequestration once released into the circulation. To explore the contribution of diminished deformability and increased fragility to these in vivo phenomena, iron status was correlated with the corresponding in vitro measurements using ektacytometry on whole erythrocytes or resealed ghost membranes. Compared to normal controls (Group 1: n = 15), those with iron deficiency of unknown origin (Group 2: n = 15), or when associated with primary proliferative polycythemia (Group 3: n = 20), were significantly less deformable and more fragile, whereas the latter category of patients, who were not anaemic (Group 4: n = 33), occupied an intermediate position. These observations support the contention that shortened intramedullary and extramedullary lifespan is contributed to by the altered physical characteristics of the red cell membrane. This observation is therapeutically important since the lesion can be readily corrected by oral iron supplementation which, at the same time, reverses the symptoms of the anaemia and prevents the development of paradoxical hyperviscosity. Additionally, it is speculated that the risk of thrombotic events in the polycythemic group may be reduced, since these appear to occur more frequently in the face of depleted body iron stores.