ESR Test (Erythrocyte Sedimentation Rate)

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KEY POINTS

• The erythrocyte sedimentation test is a blood test to check for some diseases causing inflammation in your child’s body. It can help diagnose a medical problem or check how well treatment for some diseases is working.
• A small amount of blood is taken from a vein in your child’s arm with a needle and sent to a lab.
• Talk to your healthcare provider about what the test results mean and ask any questions you have.

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What is the ESR test?

The erythrocyte sedimentation rate (ESR) blood test is done to check for diseases causing inflammation in your child’s body. The test measures how far red blood cells (erythrocytes) fall in a test tube in 1 hour. When inflammation is present, the red blood cells fall farther and clump together.

The ESR is also called the sedimentation rate, or sed rate.

Why is this test done?

The ESR test may help diagnose and treat a medical problem your child is having. It does not diagnose a specific problem but it can help the healthcare provider know what other tests your child might need. It’s also a way to see how well treatment for some diseases is working.

How do I prepare my child for this test?

• Your child may need to avoid taking certain medicines before the test because they might affect the test result. Tell your child's healthcare provider about all the medicines and supplements your child takes. Ask your provider before stopping any of your child’s regular medicines.
• Talk to your healthcare provider if you have any questions about the test.

How is the test done?

A small amount of blood is taken from a vein in your child’s arm with a needle. The blood is collected in tubes and sent to a lab.

Ask your child’s healthcare provider how and when you will get your child’s test results.

What do the test results mean?

When there is inflammation in the body, the red blood cells stick together more than normal and fall to the bottom of the test tube more quickly. Your child’s ESR may be higher than normal if your child has a disease or problem that is causing inflammation such as:

• Autoimmune disease (a disease that causes your body to mistakenly attack your own tissues, like lupus or juvenile idiopathic arthritis)
• Kawasaki disease, which causes inflammation of the walls of blood vessels, especially heart arteries
• Infection
• Cancer

Some diseases cause inflammation but do not raise the ESR, so a normal result does not always mean that your child does not have a medical problem. A low ESR is usually not a problem. However, your child’s ESR may be lower than normal if your child has:

• A disease or condition that increases red blood cell production
• A disease or condition that increases white blood cell production
• Sickle cell anemia (abnormal red blood cells)

If your child is being treated for an inflammatory disease, an ESR that is going down is often a good sign that your child’s body is responding to the treatment.

What if my child’s test result is not normal?

Test results are only one part of a larger picture that takes into account your child’s medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about the result and ask questions such as:

• If your child needs more tests
• What kind of treatment your child might need
• What lifestyle, diet, or other changes your child might need to make