The erythrocyte sedimentation rate (ESR) test is a blood test. It helps healthcare providers check for inflammation inside your body. They might use it to help diagnose a condition or infection, or to monitor you for changes after starting a new treatment. It’s a quick, simple test with no special preparation and no side effects.
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The erythrocyte sedimentation rate (ESR) test is a blood test healthcare providers use to detect inflammation in your body. Providers usually refer to it by the shortened name sed rate test or ESR test.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
An ESR blood test can’t confirm or rule out any diseases or conditions. It can’t make a specific diagnosis. But it can show your provider if there are signs of inflammation in your body. They’ll use that result along with other tests, a physical exam and any symptoms you’re experiencing to narrow down a diagnosis.
Your healthcare provider can use an ESR test to help diagnose or monitor inflammatory conditions. Inflammation happens when your immune system activates special cells after an injury or to fight things like viruses, bacteria or toxins. But inflammation can damage your body if you have too much, or if it lasts for too long.
Your provider may suggest a sed rate test if you have symptoms of an inflammatory condition, like:
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You don’t need to do anything special to get ready for a sed rate test. You should be able to eat, drink and take all of your usual medications and supplements.
The ESR test is a simple blood test. A phlebotomist or your healthcare provider will remove a small amount of your blood from a vein (usually in your arm).
ESR is a measure of your erythrocyte sedimentation rate. Erythrocyte is the medical name for a red blood cell. A sedimentation rate is how long it takes a substance to fall to the bottom of a container of liquid. So, your erythrocyte sedimentation rate (ESR) is how long it takes your red blood cells to fall to the bottom of a sample of your blood in a vertical container.
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Picture a lava lamp where the gel inside floats up and down as the light at the bottom heats and cools it. In this case, a vial of your blood is the lamp, and there’s no heating element. Your provider will time how long it takes your red blood cells to settle to the bottom of the test tube.
If it happens faster than usual, you might have an inflammatory condition.
Your provider or phlebotomist will wipe an antiseptic on your arm and insert a needle into your vein. They may ask you to make a fist to help blood flow to that arm.
You might feel a sharp pinch when your provider inserts the needle. Tell them if you’re nervous about needles or blood tests. They’ll help you relax and stay calm.
ESR blood tests are extremely safe and don’t have any risk of complications. They don’t cause side effects.
Your arm might hurt for a few hours after your test. Your provider will put a bandage on the spot where they inserted the needle. It’s normal to have minor bleeding or bruising after a blood draw.
An ESR test shows how quickly your red blood cells sink to the bottom of your blood sample. Most healthcare providers use the Westergren method. They’ll put a sample of your blood into a special vial called a Westergren tube and see how long it takes your red blood cells to sink to the bottom.
Your provider will measure the rate of red blood cell sedimentation as a speed in millimeters per hour (mm/hr). It’s like a tiny version of your car’s speedometer measuring how fast you’re driving in miles or kilometers per hour.
A normal range for ESR depends on your age and sex:
| Age and sex | Normal ESR |
|---|---|
| Males younger than 50 | Less than 15 millimeters per hour (<15 mm/hr) |
| Males older than 50 | <20mm/hr |
| Females younger than 50 | <20mm/hr |
| Females older than 50 | <30mm/hr |
| Newborn babies | 0 to 2 mm/hr |
| Children who haven’t hit puberty yet | 3 to 13 mm/hr |
| Age and sex | |
| Males younger than 50 | |
| Normal ESR | |
| Less than 15 millimeters per hour (<15 mm/hr) | |
| Males older than 50 | |
| Normal ESR | |
| <20mm/hr | |
| Females younger than 50 | |
| Normal ESR | |
| <20mm/hr | |
| Females older than 50 | |
| Normal ESR | |
| <30mm/hr | |
| Newborn babies | |
| Normal ESR | |
| 0 to 2 mm/hr | |
| Children who haven’t hit puberty yet | |
| Normal ESR | |
| 3 to 13 mm/hr |
Typical ESR ranges can vary from person to person. Some testing labs have different standard ranges, too. Your provider will share your test results and help you understand them.
Having an elevated sedimentation rate may mean there’s inflammation somewhere in your body. Your provider will talk to you about which other tests or treatments you’ll need if you have an unusually high sed rate.
A high ESR can be a sign of lots of inflammatory conditions, including:
Having a low sed rate isn’t usually a cause for concern. In fact, people usually have a sedimentation rate that’s lower than the thresholds listed above. But everyone’s body is different. Some people have an ESR that’s naturally higher or lower than usual.
A low ESR can be a sign of some issues like:
Your provider will let you know if you need other tests or follow-up exams.
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An ESR test can’t diagnose issues. It doesn’t confirm or rule out any conditions. But it’s a fast way for your healthcare provider to learn more about what’s going on inside your body. It can help them understand what might be causing the symptoms you’re experiencing. You may need another test in the future to see how your body responds to treatment.
Some people are embarrassed to admit they don’t like needles or are afraid of seeing blood. Don’t be. Tell your provider or phlebotomist if you’re nervous. They’ll help you stay calm before, during and after your ESR blood test.
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