How to Calculate Sedimentation Rate
The erythrocyte sedimentation rate (ESR) measures the rate at which red blood cells (erythrocytes) precipitate and is typically measured in millimeters per hour. This test was invented by Dr. Edmund Biernacki in 1897 and may still be called the Biernacki test. The ESR test is generally performed by automated equipment today although the actual procedure has changed little. The ESR test indicates the general level of inflammation in the blood and can be helpful in diagnosing a range of disorders.
Things You'll Need
- Blood sample
- ethylenediaminetetraacetic acid (EDTA)
- Westergren tube
- Westergren rack
Instructions
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1
Predict the normal ESR from age and gender. The maximum normal ESR can be given as Emax = (A + G)/2 where Emax is the maximum normal ESR, A is the age in years, G is 0 for males and 10 for females.
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2
Ensure quality assurance procedures for the blood collection are met. These vary by the laboratory, but in general the blood must be used within two hours and not hemolyzed or clotted. The collection tube must also be filled to the correct level and labeled correctly.
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3
Prepare the blood for sedimentation. Add ethylenediaminetetraacetic acid (EDTA) to prevent clotting and dilute the blood with citrate by 25 percent. Fill a Westergren tube to the 200 millimeter mark. A Westergren tube is a glass pipette one-foot long with a uniform diameter of 0.1 inch.
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4
Place the Westergren tube in a Westergren rack in a vertical position for one hour. The tube should remain out of direct sunlight and free of vibration. Measure the distance that the red blood cells have fallen in millimeters.
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Interpret the results. High ESR values can help diagnose a variety of diseases such as rheumatoid arthritis, chronic kidney diseases, temporal arteritis, multiple myeloma and various auto-immune diseases.
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