ESR stands for erythrocyte sedimentation rate. It is commonly called a "sed rate."
It is a test that indirectly measures how much inflammation is in the body.
A blood sample is needed. For information on how this is done, see: Venipuncture
The blood sample is sent to a lab. The test measures how fast red blood cells called erythrocytes fall to the bottom of a tall, thin tube.
There are no special preparations needed.
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
A "sed rate" is often ordered for someone who is having unexplained fevers, certain types of arthritis, muscle symptoms, or other vague symptoms that cannot be explained.
Once a diagnosis has been made, this test may be used to monitor whether the illness is becoming more active or flaring up.
This test can be used to monitor inflammatory diseases or cancer. It is a screening test, which means it cannot be used to diagnose a specific disorder.
However, it is useful for detecting and monitoring:
Adults (Westergren method):
Children (Westergren method):
Note: mm/hr. = millimeters per hour
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
Although it can help diagnose some illnesses, an abnormal ESR does not prove that you have a certain condition. Other tests are almost always needed.
An increased ESR rate may be due to:
The immune system helps protect the body against harmful substances. In autoimmune disorder is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. ESR is often higher than normal in people with an autoimmune disorder.
Common autoimmune disorders include:
Very high ESR levels occur with less common autoimmune disorders, including:
An increased ESR rate may be due to some infections, including:
Lower-than-normal levels occur with:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Erythrocyte sedimentation rate; Sed rate; Sedimentation rate
Kushner I, Ballou SP. Acute-phase reactants and the concept of inflammation. In: Firestein GS, Budd RC, Harris ED, et al, eds. Kelley's Textbook of Rheumatology. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 52.
Pisetsky DS. Laboratory testing in the rheumatic diseases. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 278.
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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