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.
How the Test is Performed
A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand. 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 steps needed to prepare for this test.
How the Test will Feel
You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
Why the Test is Performed
Reasons why a "sed rate" may be done include:
- Unexplained fevers
- Certain types of arthritis
- Muscle symptoms
- Other vague symptoms that cannot be explained
This test may also be used to monitor whether an illness is responding to treatment.
This test can be used to monitor inflammatory diseases or cancer. It is not used to diagnose a specific disorder.
However, the test is useful for detecting and monitoring:
- Autoimmune disorders
- Bone infections
- Certain forms of arthritis
- Inflammatory diseases that cause vague symptoms
- Tissue death
For 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
For 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 health care provider about the meaning of your specific test results.
What Abnormal Results Mean
An abnormal ESR may help with a diagnosis, but it 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. An autoimmune disorder is 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:
- Allergic vasculitis
- Giant cell arteritis
- Hyperfibrinogenemia (increased fibrinogen levels in the blood)
- Macroglobulinemia - primary
- Necrotizing vasculitis
- Polymyalgia rheumatica
An increased ESR rate may be due to some infections, including:
- Body-wide (systemic) infection
- Bone infections
- Infection of the heart or heart valves
- Rheumatic fever
- Severe skin infections, such as erysipelas
Lower-than-normal levels occur with:
Erythrocyte sedimentation rate; Sed rate; Sedimentation rate
Pisetsky DS. Laboratory testing in the rheumatic diseases. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 257.
Review Date 5/3/2015
Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.