It's a sign of inflammation in your body, and its full name is erythrocyte sedimentation rate (ESR). It's measured through a blood test that shows how fast your red blood cells (erythrocytes) sink to the bottom of a test tube. When you have inflammation, proteins in your blood make those cells fall faster.
Also called your sed rate, it can’t tell if you have any specific health conditions. “It’s one ‘flavor’ of inflammation, but it’s not the only one,” says Kara Wada, MD, a board-certified allergist and immunologist in Columbus, Ohio.
If your result is high, your doctor may order more tests to find out why. Sometimes, it may suggest you have a condition linked to inflammation, such as an infection, an autoimmune disease, arthritis, or certain types of cancer.
Why Would You Get a Sed Rate Test?
Your doctor might order a sed rate test if you have:
- Persistent headaches
- Stiff, swollen, or painful joints
- Pain in your shoulders or neck
- A fever without a clear cause
- Weight loss without trying
- Ongoing diarrhea
If your doctor is trying to assess your health, a sed rate test may offer a clue to one piece of the puzzle.
Your doctor might also order an ESR test after you’ve started treatment for a condition linked to inflammation. The result may help show if your treatment is working.
How Is a Sedimentation Rate Test Done?
You don’t need to do anything special to prepare for an ESR test. It’s a basic blood test. Unless your doctor tells you otherwise, you don’t need to change what you eat or drink that day, and you can take your usual medicines.
At the lab, a sample of your blood is taken from a vein in your arm. First, a band is tied around your upper arm so the vein fills with blood. Then, the area’s cleaned, and a needle’s placed into your vein. Your blood collects in a small vial or tube.
The whole process usually takes just a couple of minutes. When it’s done, you’ll get gauze and a bandage over the spot to stop any bleeding.
You may feel a quick pinch or sting when the needle goes in. Tell those giving you the test if you feel anxious about needles or blood tests. They’ll help you relax and stay calm. Afterward, your arm might be a little sore.
How to Understand Sedimentation Rate Test Results
Once your blood sample is sent to the lab, a technician transfers it to a tall, thin tube and checks how far your red blood cells sink.
Normally, your red blood cells fall slowly. After an hour, there’s not much clear fluid (called plasma) at the top of the tube. “But if there’s inflammation, the cells clump together and sink faster,” Wada says.
Your sed rate result shows the space between the plasma at the top and the red blood cells at the bottom after one hour. It’s measured in millimeters per hour (mm/hour).
What are normal ESR ranges?
Typical ESR ranges depend on your age and sex. The most common reference for these ranges is the Westergren method, which gives rates in mm/hour. The table below outlines the normal ESR ranges for different age groups and sexes.
| Men younger than 50 | < 15 mm/hour |
| Men older than 50 | < 20 mm/hour |
| Women younger than 50 | 0-20 mm/hour |
| Women older than 50 | < 30mm/hour |
| Newborns | 0-2 mm/hour |
| Children before puberty | 3-13 mm/hour |
It’s normal for ESR ranges to vary from person to person. Some testing labs have different standard ranges. Your doctor or other health care provider will give you your results and explain them.
What can cause a high ESR?
A high sed rate does not always mean you have a health issue, but it may point to:
- Infection
- Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease
- Rheumatoid arthritis (an autoimmune condition in which your immune system attacks your joints)
- Systemic vasculitis (inflamed blood vessels)
- Giant cell arteritis (inflammation of your arteries, especially in your head)
- Polymyalgia rheumatica (a condition that causes stiff and painful muscles)
- Cancer
- Lupus (another autoimmune condition that can damage your skin, joints, or other parts of your body)
What can cause a low ESR?
A low sed rate is not diagnostic of any health issue. But it may sometimes indicate:
- Heart failure
- Sickle cell anemia
- Leukocytosis (too many white blood cells)
- Kidney issues
- Liver issues
What other tests are done after a sed rate test?
Your doctor will review your symptoms, compare them to the lab results, and “try to make sense of all of it together,” Wada says. “Then we can decide together what that next step forward is.”
They may refer you to a specialist or order more tests. That’s because a sed rate test can only show that you have inflammation somewhere in your body, not where it is or what’s causing it.
Your doctor may also order a blood test that checks your levels of C-reactive protein (CRP). This is made by your liver when you have inflammation in your body. But you’ll also probably need imaging tests, or even biopsies, before your doctor can make a specific diagnosis.
Talk to your doctor about the results of your sed rate test and any other tests you have. Make sure you understand what they mean.
“Any result needs to be thoughtfully considered along with what’s going on clinically,” Wada says. “There are a lot of reasons why your ESR may be high that aren’t catastrophic.”
Factors That May Affect Your Sed Rate
Here are some factors that can affect your ESR directly or indirectly:
- Your age and sex
- Your diet
- Chronic kidney disease
- Hyperthyroidism
- Some types of cancer
- Smoking
- Extreme obesity
- The lab’s measurement technique
Women tend to have a higher ESR, largely due to hormone shifts during menstruation, pregnancy, and menopause. Different medications can affect your sed rate, too. Some, including birth control pills, dextran, methyldopa (Aldomet), theophylline, and vitamin A, can increase your ESR. Others, such as aspirin, quinine, and steroids, can lower your ESR.
Your doctor will consider all these things when they view your ESR results.
“We have really great labs now that we didn’t have decades ago. And also, they’re not perfect,” Wada says. “It’s always really important, when we think about any lab test, to understand that there can be levels that are falsely positive. There also can be levels that are falsely negative.”
Takeaways
A sedimentation rate test, or ESR test, shows if you have inflammation in your body. But it can’t tell you where the inflammation is, or what’s causing it. It also can’t diagnose a specific condition. If your sed rate isn’t in the normal range, your doctor may order more blood tests or imaging tests to find out why.
Sedimentation Rate FAQs
Can stress affect ESR levels?
So far, research hasn’t shown a solid link between stress or anxiety and ESR level. But that may change as more studies are done. Some studies show that people who are depressed or have suicidal thoughts have higher ESR.
Can high ESR be temporary?
Many conditions can cause your ESR to rise for a short time. So, your doctor may want you to have another sedimentation rate test a few weeks or months after you have your first one.
Is it better to have a high or low sedimentation rate?
Ideally, your sedimentation rate should fall within the normal range, but a high or low result isn’t always cause for concern. Everyone is slightly different. An abnormal result doesn’t always mean you have a health issue.
Is fasting required before an ESR test?
You usually don’t need to fast before an ESR test. But check with your doctor. They may want you to do other lab tests at the same time, and some of those might require you not to eat or drink beforehand.
What cancers do a high sed rate indicate?
The ESR test isn’t diagnostic, meaning it can’t tell if you have cancer or what type. But a higher ESR may sometimes be linked to lymphoma, multiple myeloma, some tumors, and other malignancies.