Production of Spherocytosis and Increased Osmotic Fragility in Normal Erythrocytes by Sodium Stress

Red cells from normal human subjects were exposed to hypertonic sodium chloride solutions for varying periods of time. The cell changes commonly observed in hereditary spherocytosis were induced, including microspherocyte formation with corresponding increase in osmotic fragility. Solutions of magnesium sulphate of equal osmolarity did not produce these changes. These observations lend support to the theory that excessive sodium permeability is concerned in the pathogenesis of hereditary spherocytosis. Increased influx of sodium and water into erythrocytes leads to spherocytosis, but only increased efflux of sodium leads to irreversible microspherocytosis.