Osmotic fragility of normal and sickle haemoglobin containing red blood cells.

Abnormalities in osmotic fragility have been observed in hereditary spherocytosis, hereditary elliptocytosis, pyruvate kinase deficiency, thalassaemia and iron-deficient red cells (1). Harris et al have reported a decrease in osmotic fragility of the red cells of sickle cell anaemia patients from Africa (2). The Indian patients are genetically and clinically different from the African patients (3). Though the abnormalities in the glucose metabolism and a greater loss of K+ion from the red blood cells of our patients during incubation have been reported (4, 5), data pertaining to the osmotic fragility of these cells are not available. Therefore, we have estimated the osmotic fragility curve of both fresh and incubated red blood cells of the homozygous sickle cell disease patients.