The osmotic fragility test in hereditary spherocytosis

This figure shows results of an incubated osmotic fragility test performed on red cells from an adult patient with hereditary spherocytosis, showing markedly increased osmotic fragility. Note that the patient's red cells were >60 percent hemolyzed at a saline concentration (0.7 g/dL) that did not cause any osmotic lysis in normal, incubated red cells.