Diseases Exposed: ESR Test in the Classroom
A rack of erythrocyte sedimentation rate (ESR) tubes.Copyright 2004 Tristanb, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Esrrack_350px.jpg
Students demonstrate the erythrocyte sedimentation rate test (ESR test) using a blood model composed of tomato juice, petroleum jelly and olive oil. They simulate different disease conditions, including rheumatoid arthritis, anemia, leukocytosis and sickle-cell anemia, by making appropriate variations in the particle as well as in the fluid matrix. Students measure the ESR for each sample blood model, correlate the ESR values with disease conditions and confirm that diseases alter blood composition and properties. During the activity, students learn that when non-coagulated blood is let to stand in a tube, the red blood cells separate and fall to the bottom of the tube, resulting in a sediment and a clear liquid called serum. The height in millimeters of the clear liquid on top of the sediment in a time period of one hour is taken as the sedimentation rate. If a disease is present, this ESR value deviates from the normal, disease-free value. Different diseases cause different ESR values because blood composition and properties, such as density and viscosity, are altered differently by different diseases. Thus, the ESR test serves as a real-world diagnostic screening test to identify indications of the presence of any diseases in people.
Sedimentation is a popular industrial technique for the separation of solids from solution-based heterogeneous mixtures by gravitational force and is used in food, beverage, pharmaceutical, paper and pulp, and clean water industries. The sedimentation principle is also utilized in the medical industry in clinical tests developed by biomedical engineers. In fact, the medical industry benefits so much from the sedimentation technique that it is put to use every day in hospitals around the world. The erythrocyte sedimentation rate (ESR) test is a popular clinical test and is solely based on the sedimentation principle. Chemical engineering and biotech processes frequently employ the sedimentation process in the separation of powders into fractions, isolation of various products in food processing, pharmaceuticals, pigment production, mineral beneficiation, drinking water industry, wastewater treatment, marine sedimentation, and in the silting of rivers and dams.
After this activity, students should be able to:
- Show that the ESR clinical test is based on the sedimentation technique for blood separation.
- Explain that the mass, size and shape of erythrocytes influence the ESR value.
- Demonstrate that the density and viscosity of the fluid influences the ESR value.
- Demonstrate the ESR test using a blood model.
- Simulate different disease conditions in the ESR test.
- Explain that pursuing college level courses in science, math and engineering can aid in securing jobs in the clinical medical industry.