1. Fragility of Erythrocyte

2. Outline  Introduction  Purpose  Principle  Materials  Procedure  Results  Discussion

3. Introduction  The osmotic fragility test (OFT) is used to measure erythrocyte resistance to hemolysis while being exposed to varying levels of dilution of a saline solution.  When erythrocytes are exposed to a hypotonic environment, water enters the cell and causes swelling and eventually lysis.  RBC are exposed to a series of saline (NaCl) solutions with increasing dilution. The sooner hemolysis occurs, the greater is osmotic fragility of RBC

4. Purpose  Understand the resistance of erythrocyte in response to hypotonic solutions, and learn the hemolytic grade of blood cells for the diagnosis of clinical disease.

5. Principle (1/2)  Normal erythrocytes of human is not hemolysis at 0.5% NaCl solution.  In physiological experiment, a 0.5% of NaCl is used as tolerance concentration to assay the fragility of erythrocyte. Normal range 1.Hemolysis onset at: 0.45-0.5% of NaCl 2.Hemolysis complete at 0.3-0.33% of NaCl Factors affecting of fragility of erythrocyte 1.Cell membrane permeability 2. surface-to-volume ratio

6. Principle (2/2)

7. Materials 1.Test tubes x 12 2.Tube rack 3.Dropper 4.Blood cells 5.Distilled water 6.0.5 % NaCl 7.Micro-pipettor

8. Procedure (1/2)  Prepare the saline(NaCl) solution of concentration of 0.5% and 0.9%.  Take 12 test tubes and place in the stand.  Deliver 0.5% of NaCl solution in first 10 test tubes and 0.9% NaCl and distilled water in another two tubes.  Place a drop of blood cells in the each tube and stand at room temperature for 30~40 minutes.  Observe the test tubes

9. Procedure (2/2) Tube No.1234567891011 Drops of the distilled water 012345678925 Drops of the 0.5 % NaCl 252423222120191817160 Concentration of NaCl (%) 0.50.480.460.440.420.400.380.360.340.32 Table 1 Concentration of NaCl and Water

10. Results (1/2) Grades of hemolysisTube No.Concentration (NaCl) Non-hemolysis1 0.5 Hemolysis 2-40.48-0.44 Partial hemolysis 5-100.42-0.32 Complete hemolysis 10-110.30-0

11. Results (2/2) Figure 1 Test tubes with concentration of 0.32- 0.5% of NaCl Figure 2 Test tubes of 0.9% Nacl and pure water

12. Discussion  The osmotic fragility of freshly taken RBCs reflects their ability to take up a certain amount of water before lysing.  The ability of the normal RCB to withstand hypotonicity results from its biconcave shape.  Allow the cell to increase its volume by about 70% before the surface membrane is stretched.  Decreased fragility of erythrocytes causes 1.Thalassemia- 2. Sickle cell anemia- 3.Iron deficiency anemia