ESR Test
Also known as: Erythrocyte Sedimentation Rate, Sed Rate, Sedimentation Rate
What is ESR?
ESR (erythrocyte sedimentation rate) measures how quickly red blood cells settle at the bottom of a test tube. Faster settling indicates inflammation.[MedlinePlus (NIH)]
What This Test Measures
This test measures the rate at which red blood cells fall in a test tube over one hour, expressed in mm/hr.[Mayo Clinic]
Why It's Important
ESR is a nonspecific marker of inflammation, used to detect and monitor inflammatory conditions.[MedlinePlus (NIH)]
ESR is particularly useful for monitoring polymyalgia rheumatica, temporal arteritis, and rheumatoid arthritis.[Cleveland Clinic]
Who Should Get This Test?
ESR helps detect and monitor inflammation, particularly in certain rheumatic diseases.
Risk Factors
- Symptoms suggestive of polymyalgia rheumatica or giant cell arteritis
- Suspected or known rheumatoid arthritis
- Monitoring inflammatory bowel disease activity
- Unexplained fever or weight loss
- Suspected infection (osteomyelitis, endocarditis)
- Symptoms of temporal arteritis (headache, vision changes)
- Monitoring response to treatment for inflammatory conditions
- Screening for certain cancers (multiple myeloma)
Screening Schedule
Ordered when inflammatory disease is suspected; repeated to monitor disease activity and treatment response.
What Happens During the Test
A blood sample is drawn from a vein and placed in a tall, thin tube. The distance red blood cells fall in one hour is measured in millimeters.
Duration
5-10 minutes for blood draw; test itself takes 1 hour; results same day
Discomfort Level
Minimal discomfort from needle insertion
Risks & Side Effects
Standard blood draw with minimal risks.
- •Brief pain at needle site
- •Small bruise may develop
- •Rare: lightheadedness
- •Very rare: infection at puncture site
Normal Range
Men: 0-15 mm/hr (under 50) or 0-20 mm/hr (over 50). Women: 0-20 mm/hr (under 50) or 0-30 mm/hr (over 50).
Note: ESR naturally increases with age.
Source: MedlinePlus (NIH)Unit Conversion
Convert between mm/hr and mm/hr
| mm/hr | mm/hr |
|---|---|
| 10 | 10 |
| 20 | 20 |
| 40 | 40 |
| 60 | 60 |
| 100 | 100 |
High Values
High ESR indicates inflammation from infections, autoimmune diseases, cancer, or tissue damage. Very high ESR (>100) suggests serious disease.[Mayo Clinic]
Low Values
Low ESR is normal and may also be seen with polycythemia, sickle cell disease, or extreme leukocytosis.[Cleveland Clinic]
Test Limitations & Accuracy
ESR is a nonspecific test with several limitations:
- ⚠Cannot identify the source or type of inflammation
- ⚠Affected by age (increases naturally with age)
- ⚠Affected by anemia (higher ESR) and polycythemia (lower ESR)
- ⚠Pregnancy increases ESR
- ⚠Obesity can elevate ESR
- ⚠Some medications affect ESR (oral contraceptives, aspirin)
- ⚠Slower to rise and fall than CRP in acute conditions
- ⚠Technical factors (temperature, tube angle) affect results
Alternative & Complementary Tests
ESR is often ordered alongside other inflammatory markers:
Rises and falls faster than ESR; more sensitive for acute inflammation
For cardiovascular risk assessment
WBC count and other markers of infection/inflammation
Alternative to ESR; less affected by anemia
Acute phase reactant; also used to assess iron stores
References
Medical Disclaimer
This information is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for interpretation of test results and medical decisions.
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