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Erythrocyte Sedimentation Rate (ESR) – Serum

Published: August 9, 2026Updated: August 17, 2026

This test measures how quickly red blood cells settle in a sample of your blood over time. It’s often used to check for inflammation in your body.

Quick summary

["ESR helps detect inflammation, which can signal conditions like infections, autoimmune diseases, or other health concerns."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
4539-3
Short code
Erythrocyte Sed Rat Bld Zeta
Synonyms
Erythrocyte Sed Rat Bld Zeta
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
zeta
CPT
85041
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What ESR Measures

ESR works by placing a sample of your blood in a tube with a marked line. Over a set period (usually 1 hour), red blood cells gradually fall toward the bottom. The distance they travel is measured and recorded as your ESR value. This process reflects how sticky or clumped together your red blood cells are, which can change with inflammation.

Why ESR Matters in Your Health

While ESR isn’t the only test for inflammation, it can help doctors identify whether your body is responding to an infection, injury, or an autoimmune condition. It’s often used as a screening tool rather than a definitive test.

Common Uses for ESR Testing

Doctors may order ESR tests to monitor conditions like rheumatoid arthritis, lupus, infections (such as pneumonia or tuberculosis), or after surgery to check for healing responses. It can also be part of routine check-ups for certain symptoms, like fatigue or unexplained fevers.

What to Expect Before or After the Test

This test is quick and painless. You’ll have a small needle inserted into your arm to draw blood, similar to other blood tests. No special preparation is needed, but let your doctor know if you’re on blood thinners or have a history of bleeding issues.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

ESR

Frequently asked questions

What does an ESR result mean?
An ESR result alone doesn’t diagnose a condition but can signal inflammation. High ESR may suggest infections, autoimmune diseases, or other inflammatory processes. Low ESR might indicate no active inflammation or certain blood disorders. Always discuss your results with your healthcare provider, as they’ll consider your full medical history and other test results.
How often should I get an ESR test?
Your doctor will determine how often you need an ESR test based on your symptoms, medical history, and other tests. Some people may need it yearly or more frequently if they have ongoing health conditions like arthritis or heart disease.
Can lifestyle changes affect ESR?
Yes, lifestyle factors like diet, exercise, and stress can influence inflammation levels. While ESR itself doesn’t change with lifestyle changes, managing conditions like high blood pressure or diabetes may help keep inflammation in check. Always follow your doctor’s advice for managing any underlying health concerns.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy