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BACKGROUND
The osmotic fragility test (OFT) is used for the measurement of erythrocyte resistance to the hemolysis when it is exposed to varying amounts of diluted saline solution. When the erythrocytes are exposed to saline solution, water enters the cell causing swelling and in turn it causes lysis of the cell. This was originally described by Parpart et al.1
The osmotic fragility is increased in hereditary spherocytosis and hypernatremia, and decreased in chronic liver disease, iron deficiency anemia, thalassemia, hyponatremia, polycythemia vera and sickle cell anemia after splenectomy.2
The aim of the experiment is determination of osmotic fragility of erythrocytes.
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REQUIREMENTS
Subjects: Human
Apparatus: Test tubes
Heparinized blood
Hypotonic solution (distilled water)
Hypertonic solution
Isotonic solution (normal saline)
Centrifuge
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PROCEDURE
Prepare the three test tubes, each of hypotonic solution, hypertonic solution and isotonic solution. Mix few drops of heparinized blood in each tube using a stirrer or manually. Place all the three samples in centrifuge.
The hypotonic solution will be colored due to swelling and rupture of the erythrocytes and hemoglobin release. The isotonic solution will show no change in color as the RBCs is intact. The hypertonic solution will also be colored due to the shrinking of RBC and destruction of plasma membrane and hemoglobin release.3
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CONCLUSION
This testing is used in diagnosis of hereditary spherocytosis, thalassemia, Iron deficiency anemia, sickle cell anemia, severe burns and poisoning.
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REFERENCES
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https://emedicine.medscape.com/article/2085814-overiview#a3. Accessed on 06 April 2018.
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https://en.m.wikipedia.org/wiki/Erythrocyte-fragility. Accessed on 06 April 2018.
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https://www.slideshare.net/mobile/fateh11/osmotic-fragility-test. Accessed on 06 April 2018.
