Practical Physiology: Erythrocyte Sedimentation Rate (ESR)

Erythrocyte Sedimentation Rate (ESR)

• ESR stands for Erythrocyte Sedimentation Rate
• Westergren tube is used to measure ESR, allowing RBCs to settle and measure the rate of sedimentation
• Wintrobe method is used for ESR measurement, which provides a more accurate result
• ESR result is typically reported in mm/h
• High ESR level indicates inflammation, infection, or tissue damage
• ESR test is a non-specific measure of inflammation, as it does not specify the cause of inflammation
• Wintrobe tube should be placed in an isolated area free from vibrations to ensure accurate results
• Presence of agglutinated RBCs can lead to a false high result in ESR
• Standard amount of anticoagulant should be used in the Wintrobe tube to prevent clotting
• Anemia can lead to an increased ESR
• Decreased ESR can be caused by high RBC count, sickle cell anemia, or polycythemia vera
• Room temperature should be regulated during ESR testing to prevent temperature-related errors
• Plasma albumin plays a role in the sedimentation of RBCs
• Factors that can increase ESR include inflammation, infection, and tissue damage
• Primary cause of a false high result in ESR testing is the presence of agglutinated RBCs
• If the Wintrobe tube is not placed absolutely vertical to the table, it can lead to inaccurate results

Osmotic Fragility Test

• Osmotic fragility test is used to diagnose hereditary spherocytosis
• Osmosis is the movement of solvent particles across a semipermeable membrane from higher to lower concentration
• Diffusion is the movement of particles from higher to lower concentration
• Red blood cells in a hypertonic solution shrink and become more permeable
• Isotonic solution signifies equal concentration of solutes inside and outside the cell
• Osmosis is the process of moving solvent particles across a semipermeable membrane from higher to lower concentration
• Hypotonic solution causes cells to swell and eventually lyse
• Red blood cells in an isotonic solution maintain their shape and size
• Molarity of a solution with 2 moles of solute in 1 liter of solution is 2M
• Hemolysis starts at 0.48% NaCl concentration
• Osmolarity is directly proportional to the number of active particles in a solution
• Centrifugation is used to separate the supernatant from the red blood cells
• Hemolysis completes at 0.30% NaCl concentration
• In spherocytosis, hemolysis starts earlier, at around 0.60% NaCl concentration
• Formula for calculating osmolarity is osmolarity = Σ(n × φ)
• One osmotically active particle represents 1 mole of solute per liter of solution