The erythrocyte sedimentation rate (ESR) test is a blood test used to check for inflammation in the body. The ESR is also called the sed rate.
The test measures how many of your red blood cells (erythrocytes) fall to the bottom of a test tube in 1 hour. When there is inflammation in the body, the red blood cells to stick together more than normal and so they fall more quickly than normal. This means that more red blood cells fall to the bottom of the test tube in 1 hour than when there is no inflammation in the body. The more red blood cells that fall to the bottom, the higher the ESR is.
The ESR test may help your healthcare provider diagnose and treat a medical problem you are having. A high ESR suggests that you may have a disease that is causing inflammation, such as an infection or arthritis or other autoimmune diseases. It cannot show exactly what is causing your illness but it can be an important test for narrowing down the list of possible causes. It can help your provider know what other tests you might need.
The ESR test may also be a way to see how well your treatment for a disease is working. If your treatment is reducing inflammation, your ESR will be lower.
The ESR is a test often used to diagnose and check the effectiveness of treatment for the diseases temporal arteritis and polymyalgia rheumatica.
Usually no preparation is needed for this test.
A small amount of blood is taken from your arm with a needle. The blood is collected in tubes and sent to a lab for testing.
Having this test will take just a few minutes.
Ask your healthcare provider when and how you will get the results of your test.
The normal range for the ESR varies with age and gender. Normal ranges may be different from lab to lab. They are usually shown in parentheses next to your test results on the lab report. Talk to your healthcare provider for an interpretation of your test results.
Any disease that causes inflammation may increase the ESR. Common examples include: arthritis, autoimmune diseases, infection, and cancer. The ESR is also higher during pregnancy or if you have kidney or thyroid disease. Many medicines can also affect the results of this test. Make sure that your healthcare provider knows about all of the medicines you are taking.
Some diseases cause inflammation but do not raise the ESR, so a normal result does not necessarily mean that you do not have a medical problem.
Many things can cause a high ESR. Your healthcare provider will use the result of your ESR test, the history of your illness, your physical exam, and any other tests you may have had to arrive at a diagnosis.
The ESR may be tested again over weeks or months to follow the course of your illness or to see how well your treatment is working.
Talk to your healthcare provider about your result. Ask your provider:
