Erythrocyte osmotic fragility test

This test measures the resistance of red blood cells to hypotonic solutions of various concentrations. In hypotonic saline, water penetrates the cell membrane, causing the red blood cells to gradually expand and destroy. The permeability of red blood cells mainly depends on the ratio of surface area to volume of red blood cells. Those with a large surface area and a small volume are more resistant to salt infiltration solution, otherwise they are less resistant (increased brittleness). The surface area / volume ratio of spherical red blood cells is reduced, which is particularly sensitive to hypotonic solutions, and the brittleness is significantly increased.