Sedimentation Rate: About This Test

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What is it?

The sedimentation rate (sed rate) test is a blood test that measures how quickly red blood cells settle in a test tube. When inflammation is present in the body, the red blood cells stick together and fall more quickly than normal to the bottom of the tube.

Why is this test done?

A sed rate test is done to:

  • Find out if inflammation is present.
  • Check on the progress of a disease.
  • See how well a treatment is working.

How can you prepare for the test?

  • In general, you don’t need to prepare before having this test. Your doctor may give you some specific instructions.

What happens during the test?

  • A health professional takes a sample of your blood.

What else should you know about the test?

  • Your results will include an explanation of what a "normal" result is. This is called a "reference range." It is just a guide. Your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed may still be normal for you.
  • There are many possible causes of a high sed rate. For this reason, the test is done with other tests to confirm a diagnosis.
  • Some diseases that cause inflammation don't increase the sed rate, so a normal sed rate doesn't always rule out a disease.

How long does the test take?

  • The test will take a few minutes.

What happens after the test?

  • You will probably be able to go home right away.
  • You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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