Increased Permeability of Erythrocyte Membrane in Thalassemia

Increased sodium efflux is demonstrated in vitro in thalassemic red blood cells (and in those of patients with some other hemolytic conditions). This increase, in the presence of either normal or augmented sodium accumulation, must reflect an increased sodium leak into the cells. In vivo, the intracellular content of sodium and potassium is nearly normal. In vitro, however, thalassemia major RBC incubated for 24 hr undergo increased sodium gain, with somewhat more potassium loss. The resultant loss of cations presumably leads to intracellular dehydration. The converse obtains in hereditary spherocytosis, insofar as a sodium gain greater than the potassium loss leads to accumulation of water. It is concluded that increased permeability of the erythrocyte membrane often reflects an underlying hemolytic process. It is postulated that inability to maintain a normal composition of cations and water plays a part in the pathogenesis of hemolysis in thalassemia.