A patient seated in the chair before a blood draw
In person

Sed Rate (ESR)

An indirect read on inflammation, from one standard blood draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
None
Nothing to do ahead of time. Water is fine.
Results
1 to 2 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

The sed rate, or erythrocyte sedimentation rate (ESR), measures how quickly red blood cells settle to the bottom of a tube. Inflammation adds proteins to the blood that make cells clump and fall faster. ESR changes more slowly than CRP, so the two are often read together. No fasting is needed.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

This test is for adults whose healthcare provider wants to check or follow inflammation, often with joint pain, a known autoimmune condition, or a past result.

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows how fast your red blood cells settle, which can help a healthcare provider see whether inflammation may be present and follow it over time.

Erythrocyte sedimentation rate (ESR)
ESR measures how quickly red blood cells settle to the bottom of a tube. Inflammation changes proteins in the blood that make cells clump and settle faster. It is a general marker: it can rise with many conditions, as well as with age and pregnancy, and it does not point to a cause.
Why it’s measured: A general inflammation marker that does not point to a cause.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. No fasting needed, and nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 2 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

ESR is reported in millimeters per hour (mm/h), the distance the cells settle in an hour, and compared with the lab’s reference range.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

A raised ESR has many possible causes and is not specific, so a healthcare provider reads it with your symptoms and other tests.

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

Blood is placed in a tall, thin tube, and the lab measures how far the red blood cells fall in an hour. When there is inflammation, certain proteins in the blood make red cells stick together, so they settle faster. A faster rate suggests inflammation, but not where it is.

Both are general signs of inflammation. CRP is a protein that rises and falls fairly quickly, while ESR tends to change more slowly. CRP is also useful for following inflammatory conditions, so a healthcare provider may check both.

ESR is not specific. It tends to be higher with older age and in women, and it can be affected by anemia, pregnancy, and some other conditions. That is why a result is read in context rather than on its own, and why it cannot tell you what is causing a change.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.