<prompt> All of the following are true of 3 thalassemia major, except-SplenomegalyTarget cells on peripheral smearMicrocytic hypochromic anemiaIncreased osmotic fragility  <response>: Ans. is d i.e. increased osmotic fragility Osmotic fragility test o Red cells are suspended in a series of tubes containing hypotonic solutions of NaC1 varying from .9 to 0.0 incubated at room temperature, for 30 minutes and centrifuged. o The percent hemolysis in the supernatant solution is measured and plotted for each NaC1 concentration. o Cells that are more spherical, with a decreased surfacevolume ratio have a limited capacity to expand in hypotonic solutons and lyse at a higher concentration of Nacl than do normal biconcave cells. o These cells are said to have increased osmotic fragility and are seen in hereditary spherocvtosis o Conversely, cells that are hypochronic and flatter have a greater capacity to expand in hypotonic solutions, lyse at lower concentration, are said to have decreased osmotic fragility. o These cells with increased surfacevolume ratio are osmotically resistant and are seen in iron deficiency, thalassemia, liver disease and reticulocytosis. 