Patient education: Erythrocyte sedimentation rate (The Basics)

What is an erythrocyte sedimentation rate? — An erythrocyte sedimentation rate, or "ESR," is a blood test. It measures how quickly red blood cells stick together. It is sometimes called a "sed rate."

Different things can affect the ESR. One of the main causes is inflammation in the body. This can happen with different health conditions. But other things that are not health problems can also affect the ESR. These include pregnancy, obesity, and older age.

Doctors often order an ESR along with other tests.

Why might I get an ESR? — Your doctor might order an ESR to check for certain health problems.

Some conditions that cause a high ESR include:

●Infection

●Kidney disease

●Certain autoimmune diseases – An "autoimmune" disease is when cells in the body's infection-fighting system, called the immune system, start attacking the body's own healthy cells. This causes inflammation. Rheumatoid arthritis and lupus are examples of autoimmune diseases.

●Cancer

Inflammation in the body can be caused by many different problems. Because of this, an ESR cannot tell you exactly what health problem you have. But it can give your doctor an idea of what might be going on in your body.

An ESR can also be used to monitor treatment of certain autoimmune diseases.

How do I prepare for an ESR? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

Your ESR will be reported as a number. If your ESR is abnormal, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is. In some cases, it is normal for a person's ESR rate to be a little bit high or low. For example, during pregnancy, the ESR increases temporarily. Other things, like obesity, smoking, and exercise, can also affect the ESR.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: Rheumatoid arthritis (The Basics)
Patient education: Lupus (The Basics)

Patient education: Rheumatoid arthritis symptoms and diagnosis (Beyond the Basics)
Patient education: Systemic lupus erythematosus (Beyond the Basics)