Erythrocyte sedimentation rate
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The erythrocyte sedimentation rate(ESR), also called a sedimentation rate, sed rate or 'Biernacki Reaction', is a non-specific measure of inflammation that is commonly used as a medical screening test.
To perform the test, anticoagulated blood is placed in an upright tube, known as a Wintrobe tube and the rate at which the red blood cells fall is measured and reported in mm/h.
When an inflammatory process is present, the high proportion of [fibrinogen] in the blood causes red blood cells to stick to each other. The red cells form stacks called 'rouleaux' which settle faster. Rouleau formation can also occur in association with some lymphoproliferative disorders in which one or more immunoglobulins are secreted in high amounts. Rouleau formation is however a physiological finding in some equidae and can be as such in felidae and suidae species, namely the horse, cat and pig respectively.
The ESR is increased by any cause or focus of inflammation. The basal ESR is slightly higher in females.
This test was invented in 1897 by the Polish doctor Edmund Biernacki. In 1918 the Swedish pathologist Robin Fåhræus declared the same. Fåhræus is still known as the inventor of ESR in the Western world although Fåhræus accepted that he wasn't the first[citation needed].
[edit] Uses
Although it is frequently ordered, the erythrocyte sedimentation rate (ESR) is not a useful screening test. It is only useful for diagnosing three diseases: myeloma, temporal arteritis and polymyalgia rheumatica (in which it may exceed 100 mm/hour).
It is commonly used for a differential diagnosis for Kawasaki's Disease.
It is also increased in some chronic infective conditions like Tuberculosis and Infective Endocarditis.
The clinical usefulness of erythrocyte sedimentation rate (ESR) is limited to monitoring the response to therapy in certain inflammatory diseases such as temporal arteritis, polymyalgia rheumatica, rheumatoid arthritis. It can also be used as a crude measure of response in Hodgkin's disease.
The use of the ESR as a screening test in asymptomatic persons is limited by its low sensitivity and specificity. When there is a moderate suspicion of disease, the ESR may have some value as a "sickness index."
An elevated ESR in the absence of other findings should NOT trigger an extensive laboratory or radiographic evaluation.
[edit] Normal Values
Note: mm/hr. = millimeters per hour.
Adults (Westergren method):
- Men under 50 years old: less than 15 mm/hr.
- Men over 50 years old: less than 20 mm/hr.
- Women under 50 years old: less than 20 mm/hr.
- Women over 50 years old: less than 30 mm/hr.
Children (Westergren method):
- Newborn: 0 to 2 mm/hr.
- Neonatal to puberty: 3 to 13 mm/hr.
