Sedimentation of erythrocytes Flashcards
What is the erythrocyte sedimentation rate?
ESR = a non-specific screening test for various diseases.
This 1 hour test measures the distance (in mm) that RBC’s settle in unclotted blood toward the bottom of a specially marked tube.
The ESR can be used to monitor the progress of inflammatory disease or malignant disease.
Although it is a screening, nonspecific test (cannot be used to diagnose a specific disorder), it is useful in detecting and monitoring tuberculosis, tissue necrosis, rheumatologic disorders, or an other wise unsuspected disease in which symptoms are vague or physical findings are minimal.
Average = 3-12mm/hour
What influences the ESR?
Fibrinogen –> will make the erythroblasts stack more and settle faster.
Number of erythrocytes and their size.
How does ESR work?
Anti-coagulated blood is placed in a tube (Westergren tube).
The rate at which RBC’s fall is measured in mm/hour.
When there is an inflammation there is a higher concentration of fibrinogen in the blood.
This causes the RBC’s to stick together forming stacks called ‘rouleaux.’
The rouleaux will sediment faster.
In sickle cell anaemia, polycythemia and congestive heart failure, the ESR is lower (takes longer time to sediment).
ESR is higher in females than in males.
