Erythrocyte sedimentation rate (ESR) in whole blood by the Westgren method
The erythrocyte sedimentation rate measures how quickly red blood cells settle in a vertical tube. A higher result can occur with inflammation, although this test does not identify the specific cause.
["An elevated ESR may signal inflammation, but it must be interpreted with your symptoms, examination, and other test results."]
Key facts at a glance
- LOINC
- 4537-7
- Short code
- Erythrocyte Sed Rat Bld Westrgrn
- Synonyms
- Erythrocyte Sed Rat Bld Westrgrn
- 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
- westergren
- 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
How the test works
Whole blood is placed in a calibrated Westergren tube and allowed to stand vertically. The distance the red blood cells settle during the specified reading period is reported as the ESR.
What the result means
A higher-than-expected ESR may be associated with infections, autoimmune or inflammatory disorders, and some other conditions. It is a nonspecific finding and does not by itself establish a diagnosis.
Factors that can affect the result
ESR may be higher with conditions such as anemia or pregnancy and may be lower with certain blood disorders or other circumstances. These influences are considered when a clinician interprets the result.
Preparation and testing
This test usually requires a whole-blood sample and generally does not require fasting. Follow any instructions from your healthcare provider, and tell the laboratory if you are pregnant or have recently received IV fluids.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
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.
An elevated ESR can support further evaluation for an inflammatory or infectious process, while a normal result does not rule out all illness. Results should be assessed alongside the medical history, physical examination, and other laboratory tests.
Short name
ESR
Frequently asked questions
Does an elevated ESR mean I have an infection?
Does a normal ESR rule out inflammation?
Do I need to fast before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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