Blood Test: Erythrocyte Sedimentation Rate (ESR)

What Is a Blood Test?

A blood test is when a sample of blood is taken from the body to be tested in a lab. Doctors order blood tests to check things such as the levels of glucose, hemoglobin, or white blood cells. This can help them look for problems like a disease or medical condition. Sometimes, blood tests can help them see how well an organ (such as the liver or kidneys) is working.

What Is an ESR Test?

An ESR test measures how far red blood cells settle to the bottle of a test tube in 1 hour. Inflammation or infection can lead to extra proteins in the blood, which can make the red blood cells settle farther in a test tube. When this happens, the ESR is higher.

Why Are ESR Tests Done?

Doctors may order an ESR test if a person has signs of or infection. They use ESR tests to follow conditions such as inflammatory bowel disease (IBD), arthritis, and lupus. ESR tests are also used to follow how well treatment for inflammation or infection is working.

What if I Have Questions?

If you have questions about the ESR test or what the test results mean, talk to your doctor.