Table of ContentsView AllTable of ContentsPurposeBefore the TestDuring the TestAfter the TestInterpreting Results
Table of ContentsView All
View All
Table of Contents
Purpose
Before the Test
During the Test
After the Test
Interpreting Results
An erythrocyte sedimentation rate, commonly referred to as a sed rate, is a blood test that is used to diagnose nonspecificinflammationin the body. An elevated (abnormally high) sed rate suggests that there is an ongoing inflammatory process, but this test doesn’t identify where it is in the body or why it’s occurring. Your healthcare provider may order this test during an evaluation for possible rheumatoid arthritis or lupus, to monitor diseases such as cancer, or for other reasons.
Purpose of Test
Inflammation is the immune system’s response to infection, disease, or injury. The inflammation can be short-term, as in the case of an infection, or it can be long-term, as with a chronic disease.
There are few risks associated with this test and there are no contraindications.
After blood is drawn into a tube, the test measures how fast the erythrocytes (red blood cells) in the blood settle to the bottom in one hour. Under normal conditions, when there is no inflammatory process or illness, red cells fall slowly.With inflammation, certain proteins in the blood, like fibrinogen, cause red cells to stick together and fall more quickly. These proteins are called acute phase reactants.
AC-reactive protein (CRP) testis often ordered along with a sed rate. Ahigh CRPis a general indicator of inflammation, and changes in inflammatory processes show up more quickly in a CRP test than in a sed rate.
Other blood tests that may be ordered at the same time as a sed rate are acomplete blood count (CBC)and acomprehensive metabolic panel (CMP).
Inflammatory and Autoimmune Diseases
If you have certain symptoms, your healthcare provider may order a sed rate as part of the diagnostic process.
Symptoms like persistentjoint painor stiffness, headache, weight loss, pain in the neck or shoulder, or loss of appetite are associated withrheumatoid arthritis(an autoimmune disease that occurs when the immune system attacks the joints), systemicvasculitis(a condition in which the blood vessels are inflamed),polymyalgia rheumatica(causes muscle pain and stiffness), andtemporal (giant cell) arteritis(vasculitis in certain arteries in the head and neck).
This test can also help diagnose certain blood disorders.
Unexplained Fever
Your healthcare provider may order a sed rate if you have a fever that doesn’t have any obvious causes.
Along with your other test results, your sed rate can help point to whether you have inflammation.
Monitor Inflammatory Diseases or Cancer
A sed rate is often ordered periodically to help assess the progression or treatment response of inflammatory disease or cancer.
As some conditions improve with treatment, it’s expected that the sed rate would decrease and approach the normal range.
If you need to have this test, your healthcare provider will talk to you about why you are having it and what they are looking for.
Be sure to tell your provider about all prescription and over-the-counter medications and supplements you’re taking. Oral contraceptives, aspirin, cortisone, and vitamin A may affect your test result.
Timing
Blood tests typically take less than five minutes once the technician is ready for you.As long as you’re feeling well after the blood draw, you’ll be able to leave right away.
Location
Your test may be at your healthcare provider’s office or you may get it at a local hospital or another facility.
What to Wear
You can wear whatever you want, but it’s helpful to wear a short-sleeved shirt.Just be aware that you will need to push or roll your sleeve up if you’re wearing long sleeves so the technician can access your vein.
Food and Drink
There are no fasting requirements for a sed rate, CRP, or CBC, so if these are the only tests you are having, you won’t need to restrict your diet.
If you are having a CMP test as well, you may need to fast for 10 to 12 hours before the test.Your healthcare provider will give you specific instructions.
Cost and Health Insurance
If you have health insurance, a sed rate test should be covered as any diagnostic test would be. Contact your insurer with any questions.
What to Bring
If you think you’ll be waiting to get your test done, you may want to bring along a book or something to do during this time.
A technician, nurse or phlebotomist will perform your sed rate test.
Pre-Test
When you check in, you may need to fill out some paperwork, such as a consent form or to give permission to share your test results with other healthcare providers. The person at the front desk will let you know.
Throughout the Test
This test usually only takes a few minutes.Once you’ve been seated, the technician will find a vein, typically on the inside of your arm, from which to draw your blood. If you have a history of fainting around blood or needles, let the technician know so precautions can be taken.
The technician will tie a piece of rubber around your arm, above the area from which your blood is drawn, to help increase pressure in the veins.After the area is cleaned with alcohol, a small, thin needle is pushed into your vein. You may feel a little poke, pinch, or sharp pain, but it should only last a moment.
As your blood is drawn, it’s placed in a tall, thin, vertical tube. At this point, you shouldn’t feel anything as long as you hold still.
Once the technician is getting close to being finished, they’ll untie the piece of rubber, then take the needle out of your arm.
Post-Test
If you’re bleeding, you may need a tissue or cotton ball pressed over the area for a bit to stop it.You will then have a bandage placed over the area to prevent contamination of the tiny skin puncture.
As long as you’re not feeling faint, dizzy, or nauseous, you can leave as soon as the puncture wound has stopped bleeding and has been covered. If you’re not feeling well, you may need a little more time to recover before you’re able to leave.
You can resume your normal activities as soon as you want to. It may take a few days for your test results to come back.
Managing Side Effects
The risks associated with any blood test are small. You may have bruising, pain, or swelling in the area in which your blood was taken.You can use ice packs on the area and take Advil or Motrin (ibuprofen) to help with pain or swelling.
There’s a minor risk of infection at the puncture site—keeping it clean and covering it with a bandage is typically enough to prevent an infection.
If the area feels warm, develops pus, or pain or swelling worsens or persists, call your healthcare provider.
The Westergren method is the usual technique used for measuring sed rate. The results are reported in mm/hr (millimeters per hour). Typically, sed rate increases with age and it tends to be higher in women. Some laboratories adjust for gender or age, while some labs don’t. The standard range can vary slightly between labs.
Standard normal sed rate:
When adjusted for age and gender, the typical reference range for the test is:
Adults (Westergren method):
Children (Westergren method):
Anormal sed ratedoesn’t necessarily mean that you don’t have inflammation or disease. This test helps give an overall idea of what’s going on when results are considered along with symptoms and other diagnostic tests. If you’re having the test to monitor an already diagnosed inflammatory condition and the results are normal, this could suggest that your treatment is working and/or you weren’t having a flare-up at the time of the test.
If yoursed rate is abnormal, keep in mind that this test can help diagnose a condition, but your sed rate alone doesn’t mean that you necessarily have a medical condition that requires treatment.You will need more tests done to definitively diagnose a specific condition.
Anelevated sed ratecan occur for a number of reasons. Some of the conditions that are commonly associated with an elevated sed rate include:
Additionally, your sed rate may be moderately higher than normal due to factors such as kidney disease, thyroid disease, certain cancers like multiple myeloma and lymphoma, pregnancy, menstruation, anemia, or aging. Your healthcare provider will take these factors into consideration if any of them apply to you when interpreting your test results.
If you already have a diagnosed inflammatory condition or cancer, your sed rate may be high at times when your disease is flaring up or not responding well to treatment.
Alower-than-normal sed ratecan occur in these blood disorders:
If your sed rate is elevated and your healthcare provider suspects that you have temporal arteritis or polymyalgia rheumatica, your sed rate test result will be one of the main supports for your diagnosis, along with the results of other tests and your signs and symptoms.Other tests to help support your diagnosis may include a CBC, electrolyte levels,creatinine,liver panel, antineutrophil cytoplasmic antibodies (ANCA) test, complement levels,urinalysis, lung function tests,echocardiogram, and other imaging tests. Treatment for these conditions depends on how severe they are but will likely include medications that suppress the immune system, which is overactive in vasculitis.
Your healthcare provider may order a blood culture if your sed rate is elevated and there’s a concern that you might have a severe infection.This is a blood test that looks for bacterial or fungal growth in your blood.
When your healthcare provider suspects rheumatoid arthritis (RA) and your sed rate is high, you will likely have a CRP, if you haven’t already, along with blood tests that detectrheumatoid factor (RF)and anti-cyclic citrullinated peptide (anti-CCP) antibodies.All of these together can help diagnose or rule out RA. Treatment for RA typically includes medications to keep symptoms under control.
If you have symptoms oflupus, in addition to your sed rate, your healthcare provider will need to do moreblood teststo look for autoantibodies, such as antinuclear antibody, anti-Smith antibody, anti-double-stranded DNA, anti-SSA, anti-SSB, and anti-RNP. Lupus is a complicated disease that can take a large number of tests to diagnose.Other common tests for lupus include urinalysis, CBC, CMP, complement levels, and imaging tests. A variety of medications are used to treat lupus, depending on its severity and symptoms.
If you’re diagnosed with an inflammatory disease or cancer, your healthcare provider may repeat this test periodically to monitor your treatment progress.In the case of an infection, you may also have this test repeated one or more times to confirm that the infection has gone away.
A Word From Verywell
The sed rate may be one of the first of many tests in your diagnostic process, so remember to take it one day at a time. If you’re anxious and stressed, try some relaxation techniques such as deep breathing, meditation, yoga, or progressive muscle relaxation. Make sure you’re taking time to do things you love and that you have a stress outlet, whether it’s an activity, a friend, or a creative pursuit. Soon enough, your healthcare provider will be able to pinpoint what’s behind your symptoms and you can start treatment to help improve your quality of life.
16 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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