A simple blood test to help detect inflammation, the sed rate test is a valuable diagnostic tool.
Sed rate (erythrocyte sedimentation rate, also known as ESR) is a simple blood test that helps detect inflammation in the body. The test measures the rate of fall (sedimentation) of red blood cells (erythrocytes) in a sample of blood placed in a tall vertical tube. Increased sed rate indicates inflammation.
Sed rate tests are also used to monitor the progress of an inflammatory disease.
A sed rate test is done through blood taken by needle from a vein in your arm.
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A sed rate test may be done when your doctor suspects you have a condition causing inflammation. Sed rate is called a nonspecific test because it does not diagnose specific illnesses but adds to the information about the presence and levels of inflammation.
A sed rate may be ordered to help in diagnosing and monitoring conditions including:
The blood is placed into a tall thin tube and the test measures the rate of fall (sedimentation) of erythrocytes (red blood cells). The red cells settle faster than normally if there is alteration of blood proteins, which indicates inflammation.
The results are the measurement, in millimeters, of the clear fluid (plasma) left at the top of the tube after a period of 1 hour.
A sed rate test is a simple blood draw from your arm. Unless your doctor gives you other instructions, there is nothing you need to do to prepare.
Last reviewed by a Cleveland Clinic medical professional on 03/14/2018.
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