ESR is the distance in millimeters that erythrocytes fall during 1 hour in a sample of venous blood (Westergren principle). Newer techniques allow the test to be performed in 30 minutes, resulting in improved turnaround time.
Normal range: 0 " “15 mm/hour in men and 0 " “20 mm/hour in women.
Use
ESR is not a good screening test because of its low sensitivity. CRP is superior to ESR because it is more sensitive and reflects a more rapid change in the patients condition. ESR may be used as a screening test to detect the presence of a systemic disease; however, a normal test does not exclude malignancy or other serious disease, although it does rule out temporal arteritis or polymyalgia rheumatica.
Finding a much accelerated ESR (>100 mm/hour) in patients with ill-defined symptoms directs the physician to search for a severe systemic disease, especially paraproteinemias, disseminated malignancies, connective tissue diseases, and severe infections such as bacterial endocarditis.
Finding a normal ESR in patients with paraproteinemia suggests the development of hyperviscosity syndrome.
ESR is also used to monitor the course or response to therapy of diseases if greatly accelerated initially.