Erythrocyte Sedimentation Rate (ESR) Test
The erythrocyte sedimentation rate (ESR) blood test measures how quickly your red blood cells settle in a test tube. A faster rate can indicate inflammation in your body, but it cannot diagnose the specific cause.
What this test measures
ESR measures the rate at which red blood cells settle at the bottom of a test tube. Inflammation causes red blood cells to clump together and sink faster, so the test helps detect inflammation.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
A high ESR test result means your red blood cells sank faster than normal. This may be from a condition that causes inflammation, such as giant cell arteritis, arthritis, systemic vasculitis, polymyalgia rheumatica, inflammatory bowel disease, kidney disease, infections, rheumatoid arthritis, heart disease, or certain cancers.
Lower-than-normal results
A low ESR test result means your red blood cells sank slower than normal. This may be caused by conditions such as polycythemia, sickle cell disease, leukocytosis, heart failure, or certain kidney and liver problems.
Frequently asked questions
What does ESR stand for?
ESR stands for erythrocyte sedimentation rate. It is also called SED rate or Westergren sedimentation rate.
How is the ESR test done?
A sample of your blood is sent to a lab. A health care professional places the sample in a tall, thin test tube and measures how quickly your red blood cells settle or sink to the bottom.
Can a high ESR diagnose a specific disease?
No, an ESR test alone cannot diagnose which condition is causing the inflammation. Your provider will use your ESR results along with your medical history, symptoms, and other tests to make a diagnosis.
What can affect ESR results besides disease?
Normal ESR levels vary by age and sex. Pregnancy, your menstrual cycle, aging, obesity, drinking alcohol regularly, exercise, and certain medicines or supplements can also affect ESR results.
What does a low ESR mean?
A low ESR means your red blood cells sank slower than normal. This may be caused by conditions such as polycythemia, sickle cell disease, a very high white blood cell count, heart failure, or certain kidney and liver problems.
Related lab tests
Sources
- MedlinePlus: Erythrocyte Sedimentation Rate (ESR) — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.