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.
Erythrocyte sedimentation rate; Sed rate; Sedimentation rate
How the test is performed
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.
How to prepare for the test
There are no special preparations needed.
How the test will feel
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.
Why the test is performed
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):
- 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
- Newborn to puberty: 3 to 13 mm/hr
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.
What abnormal results mean
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:
What the risks are
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:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
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.
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.