Test Description

What is ESR?

The Erythrocyte Sedimentation Rate (ESR) is a simple, inexpensive laboratory test that measures how quickly red blood cells (erythrocytes) settle to the bottom of a vertical tube over one hour. It serves as a non-specific marker of inflammation and is one of the oldest laboratory tests still in clinical use today. While not diagnostic for any specific condition, ESR is valuable for detecting the presence of inflammation, monitoring disease activity, and assessing response to treatment.

How Does It Work?

Under normal conditions, red blood cells settle slowly because they carry negative surface charges that cause them to repel each other. During inflammation, the liver produces acute phase reactants—particularly fibrinogen and immunoglobulins—that neutralize these negative charges, allowing RBCs to aggregate into stacks called "rouleaux." These rouleaux are denser and settle faster, producing an elevated ESR.

The test is performed by placing anticoagulated blood in a standardized vertical tube and measuring how far (in millimeters) the RBCs fall in one hour. The Westergren method is the reference standard and uses a 200mm tube.

Clinical Use

ESR is clinically useful for:

  • Screening for inflammation: Detecting occult inflammatory or infectious conditions
  • Monitoring disease activity: Tracking temporal arteritis, polymyalgia rheumatica, rheumatoid arthritis
  • Assessing treatment response: Following ESR trends during therapy
  • Supporting diagnosis: Part of diagnostic criteria for some conditions (e.g., temporal arteritis)
  • Prognostic marker: Elevated ESR associated with worse outcomes in some malignancies
Quick Reference
  • Normal Range (Males): 0-15 mm/hr (increases with age)
  • Normal Range (Females): 0-20 mm/hr (increases with age)
  • Age-Adjusted Formula: Upper limit = Age/2 (males) or (Age + 10)/2 (females)
  • Mild Elevation: 20-50 mm/hr
  • Moderate Elevation: 50-100 mm/hr
  • Marked Elevation: >100 mm/hr (often indicates serious pathology)
  • Method: Westergren method (gold standard)
  • Primary Use: Non-specific marker of inflammation; monitoring disease activity
  • Sample Type: Whole blood (EDTA tube); must be tested within 4 hours
  • Key Point: ESR is non-specific - elevated in many conditions; use with clinical context
Normal Ranges

ESR values increase with age and are higher in females than males. Several formulas exist to calculate age-adjusted upper limits of normal.

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Population Normal Range Age-Adjusted Upper Limit
Adult Males 0-15 mm/hr Age ÷ 2
Adult Females 0-20 mm/hr (Age + 10) ÷ 2
Children 0-10 mm/hr —
Elderly (>50 years) 0-20 mm/hr (males)
0-30 mm/hr (females)		 Use age-adjusted formula
Pregnancy Up to 40-50 mm/hr Physiologically elevated
Age-Adjusted Formulas:
  • Males: Upper limit = Age ÷ 2 (e.g., 70-year-old male: normal up to 35 mm/hr)
  • Females: Upper limit = (Age + 10) ÷ 2 (e.g., 70-year-old female: normal up to 40 mm/hr)

Interpretation by Level

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ESR Level Interpretation Common Causes
0-20 mm/hr Normal —
20-50 mm/hr Mild elevation Mild infection, pregnancy, anemia, aging
50-100 mm/hr Moderate elevation Active infection, autoimmune disease, malignancy
>100 mm/hr Marked elevation Multiple myeloma, temporal arteritis, severe infection, metastatic cancer
ESR >100 mm/hr: A markedly elevated ESR (>100 mm/hr) has a limited differential and should prompt evaluation for:
  • Multiple myeloma or other plasma cell dyscrasias
  • Giant cell (temporal) arteritis
  • Metastatic malignancy
  • Severe bacterial infection/sepsis
  • Chronic kidney disease
  • Connective tissue disease (SLE, RA)
Clinical Significance

Causes of Elevated ESR

Infectious Causes

  • Bacterial infections: Osteomyelitis, endocarditis, tuberculosis, abscess
  • Viral infections: Usually mild elevation; hepatitis, HIV
  • Fungal infections: Disseminated fungal disease
  • Parasitic infections: Malaria, toxoplasmosis

Inflammatory/Autoimmune Conditions

  • Giant cell arteritis: ESR typically >50 mm/hr, often >100 mm/hr; part of diagnostic criteria
  • Polymyalgia rheumatica: ESR usually >40 mm/hr; used for diagnosis and monitoring
  • Rheumatoid arthritis: Correlates with disease activity
  • Systemic lupus erythematosus: Variable elevation
  • Inflammatory bowel disease: Correlates with disease activity in Crohn's disease
  • Vasculitis: Various types show elevated ESR

Malignancy

  • Multiple myeloma: Often dramatically elevated (>100 mm/hr) due to paraproteins
  • Lymphoma: Hodgkin's and non-Hodgkin's lymphoma
  • Metastatic cancer: Especially with bone involvement
  • Renal cell carcinoma: Can present with markedly elevated ESR

Other Causes

  • Anemia: Reduced RBC mass increases sedimentation rate
  • Chronic kidney disease: Often elevated ESR
  • End-stage renal disease: May be markedly elevated
  • Pregnancy: Physiologically elevated, especially 2nd/3rd trimester
  • Obesity: Mild elevation
  • Hyperlipidemia: Can increase ESR
  • Tissue necrosis: MI, trauma, surgery

Causes of Low ESR

A low ESR is less clinically significant but can occur in:

  • Polycythemia vera: Increased RBC mass slows sedimentation
  • Sickle cell disease: Abnormal RBC shape prevents rouleaux formation
  • Spherocytosis: Abnormal RBC shape
  • Hypofibrinogenemia: Reduced fibrinogen
  • Congestive heart failure: (variable)
  • Extreme leukocytosis: WBC >50,000/μL
  • Corticosteroid use: May lower ESR
ESR vs CRP Comparison

Both ESR and C-Reactive Protein (CRP) are markers of inflammation, but they have important differences:

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Feature ESR CRP
Response Time Slow (days to rise/fall) Rapid (rises in 4-6 hours, peaks at 48 hours)
Half-life ~1 week to normalize ~19 hours
Specificity Less specific More specific for acute inflammation
Affected by Anemia Yes (falsely elevated) No
Affected by Age/Sex Yes No
Affected by Pregnancy Yes (elevated) No (or minimal)
Best Use Chronic inflammation, monitoring Acute inflammation, infection
When to Use Which:
  • ESR preferred: Temporal arteritis, polymyalgia rheumatica, monitoring chronic inflammatory conditions
  • CRP preferred: Acute infections, sepsis workup, postoperative monitoring, neonatal sepsis
  • Both together: SLE (ESR elevated, CRP often normal unless infection); discordance can be diagnostically useful
SLE Pattern: In systemic lupus erythematosus, ESR is often elevated while CRP remains normal during disease flares. If CRP becomes elevated in a lupus patient, consider superimposed infection or serositis.
Interfering Factors

Factors That Increase ESR (False Elevation)

  • Technical factors: Tilted tube, room temperature too warm, vibration, delay in testing (>4 hours)
  • Anemia: Decreased RBC mass allows faster sedimentation; this is the most common cause of falsely elevated ESR
  • Macrocytosis: Larger RBCs settle faster
  • Pregnancy: Physiologically elevated, especially 2nd and 3rd trimesters
  • Advanced age: ESR naturally increases with age
  • Female sex: Women have higher baseline ESR
  • Obesity: Associated with chronic low-grade inflammation
  • Hypercholesterolemia: Can increase RBC aggregation
  • Medications: Oral contraceptives, heparin, dextran
  • Kidney disease: ESRD patients often have elevated ESR

Factors That Decrease ESR (False Depression)

  • Polycythemia: Increased RBC mass slows sedimentation
  • Sickle cell disease: Sickled cells cannot form rouleaux
  • Spherocytosis/Acanthocytosis: Abnormal RBC shapes prevent stacking
  • Hypofibrinogenemia: Reduced rouleaux formation
  • Extreme leukocytosis: WBC >50,000/μL
  • Microcytosis: Smaller RBCs settle more slowly
  • Corticosteroids: May suppress ESR
  • NSAIDs: May mildly lower ESR
  • Technical factors: Tube too short, clotted specimen, refrigerated sample
Anemia Caveat: Always interpret ESR in the context of the patient's hemoglobin. Anemia is a very common cause of elevated ESR and can confound interpretation. Consider CRP if accurate inflammatory assessment is needed in an anemic patient.
Clinical Pearls
Temporal Arteritis Rule: In patients >50 years with new headache, jaw claudication, or vision changes, an ESR >50 mm/hr strongly supports the diagnosis of giant cell arteritis. However, up to 20% of biopsy-proven GCA cases have a normal ESR—don't let a normal result delay urgent evaluation if clinical suspicion is high.
The "Very High ESR" Differential: An ESR >100 mm/hr has a limited differential: think Multiple myeloma, Metastatic cancer, Major infection (endocarditis, osteomyelitis, TB), and Mega-inflammation (temporal arteritis, severe RA). The mnemonic "4 M's" can help.
ESR in Osteomyelitis: ESR is useful for monitoring treatment response in osteomyelitis. It rises in the first week of treatment then gradually falls. A persistently elevated or rising ESR despite antibiotics suggests treatment failure or undrained abscess.
Don't Use ESR Alone: ESR should never be used in isolation to diagnose or exclude disease. It's a supportive test that must be interpreted in clinical context. A normal ESR does not rule out serious pathology.
Monitoring Polymyalgia Rheumatica: ESR is part of the diagnostic criteria and is useful for monitoring treatment response. With corticosteroid therapy, ESR should normalize within 2-4 weeks. A persistently elevated ESR suggests inadequate treatment, non-compliance, or alternate diagnosis.
Multiple Myeloma Clue: In multiple myeloma, ESR is often dramatically elevated (>100 mm/hr) while CRP may be normal or only mildly elevated. This discordance (high ESR, low CRP) should raise suspicion for a paraprotein disorder.
Sickle Cell Caveat: ESR is unreliable in sickle cell disease because sickled red blood cells cannot form rouleaux. Use CRP instead to assess inflammation in these patients.
ESR in Pregnancy: ESR is physiologically elevated during pregnancy (up to 40-50 mm/hr in 3rd trimester) due to increased fibrinogen. Do not interpret elevated ESR as pathologic in pregnant patients without other clinical findings.
References
  1. Kratz, A., Ferraro, M., Sluss, P. M., & Lewandrowski, K. B. (2004). Laboratory reference values. New England Journal of Medicine, 351, 1548-1564.
  2. Lee, M. (Ed.). (2009). Basic skills in interpreting laboratory data. Ashp.
  3. Farinde, A. (2021). Lab values, normal adult: Laboratory reference ranges in healthy adults. Medscape. https://emedicine.medscape.com/article/2172316-overview?form=fpf
  4. Nickson, C. (n.d.). Critical Care Compendium. Life in the Fast Lane • LITFL. https://litfl.com/ccc-critical-care-compendium/
  5. Farkas, Josh MD. (2015). Table of Contents - EMCrit Project. EMCrit Project. https://emcrit.org/ibcc/toc/
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Medical Disclaimer
  • For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
  • Not a Substitute for Professional Judgment: Always consult your local protocols, institutional guidelines, and supervising physicians.
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AI Assistance Notice
The clinical content and references are curated and reviewed by myself; however, AI was used to assist in organizing, paraphrasing, and formatting the information presented.