Overview
The ESR (Erythrocyte Sedimentation Rate) test is a widely used blood test that helps detect inflammation in the body. It measures how quickly red blood cells (RBCs) settle to the bottom of a tall, thin tube over the course of one hour. Under normal conditions, red blood cells settle slowly. However, when inflammation is present, certain proteins in the blood—such as fibrinogen and immunoglobulins—increase, causing RBCs to clump together and settle faster.
Although ESR is a nonspecific test—meaning it does not diagnose one particular disease—it is extremely useful in identifying and monitoring conditions associated with inflammation, including infections, autoimmune diseases, and certain cancers.
What is the ESR Test?
The ESR test measures the rate of fall of red blood cells in a vertical test tube. The result is expressed in millimeters per hour (mm/hr). The faster the cells settle, the higher the ESR value, indicating increased inflammation.
Doctors often use ESR:
- As a basic screening test
- To support diagnosis of suspected inflammatory diseases
- To track the progress of chronic conditions
- To monitor treatment effectiveness
It is simple, inexpensive, and commonly available in all laboratories.
Where is ESR Produced in the Body?
ESR is not a substance produced by the body; it is a laboratory measurement.
However, ESR values are influenced by:
1. Plasma Proteins
Mainly produced in the liver, including:
- Fibrinogen
- C-reactive protein (CRP)
- Immunoglobulins
These proteins increase during inflammation.
2. Red Blood Cells (RBCs)
Produced in the bone marrow, RBCs affect ESR based on their:
- Number
- Shape
- Size
- Ability to settle
For example, abnormal RBC shapes (like sickle cells) lower ESR.
Importance and Functions of the ESR Test
Although nonspecific, ESR is extremely helpful in many clinical situations.
1. Detects Inflammation
Identifies inflammation anywhere in the body, even when symptoms are unclear.
2. Helps Diagnose Chronic Diseases
Especially:
- Rheumatoid arthritis
- Systemic lupus erythematosus (SLE)
- Temporal arteritis
- Polymyalgia rheumatica
- Tuberculosis
3. Monitors Disease Activity
If ESR decreases with treatment, it shows improvement.
4. Acts as a Supportive Diagnostic Tool
Often used together with:
- CRP (C-reactive protein)
- CBC (Complete Blood Count)
- Autoimmune profiles
This improves accuracy.
Causes of Low / Negative ESR Levels
Low ESR is less common and may be associated with:
1. Polycythemia
High RBC count reduces sedimentation.
2. Sickle Cell Disease
Abnormally shaped RBCs do not settle normally.
3. Severe Leukocytosis
Excess white blood cells interfere with sedimentation.
4. Low Plasma Proteins
Such as low fibrinogen levels (hypofibrinogenemia).
5. Congestive Heart Failure
Reduced sedimentation may be observed.
Symptoms Related to Low ESR
ESR itself causes no symptoms.
Symptoms depend on the underlying disease:
- Polycythemia: headache, dizziness, facial redness
- Sickle cell disease: pain crises, fatigue
- Heart failure: shortness of breath, swelling
Causes of High / Positive ESR Levels
A high ESR generally indicates inflammation or abnormal proteins in the blood.
Common causes include:
1. Infections
- Bacterial infections
- Viral infections
- Parasitic infections
2. Autoimmune Diseases
- Rheumatoid arthritis
- Lupus
- Vasculitis
- Temporal arteritis
3. Chronic Kidney Disease
High ESR may reflect chronic inflammation.
4. Cancers
Especially:
- Multiple myeloma
- Lymphoma
- Solid tumors in advanced stages
5. Anemia
Low RBC count allows faster settling.
6. Pregnancy
A normal physiological rise in ESR occurs.
Symptoms Related to High ESR
Like low ESR, high ESR does not cause symptoms.
Symptoms depend on the underlying disease:
- Fever and night sweats (infections or cancer)
- Joint pain and stiffness (rheumatoid arthritis)
- Fatigue and weight loss
- Chronic cough or chest pain (tuberculosis or lung disease)
- Headache, jaw pain, vision problems (temporal arteritis)
Reference Ranges
ESR values differ by age and gender.
Men
- Under 50 years: 0–15 mm/hr
- Over 50 years: 0–20 mm/hr
Women
- Under 50 years: 0–20 mm/hr
- Over 50 years: 0–30 mm/hr
Children
- 0–10 mm/hr
Newborns
- 0–2 mm/hr
Interpretation depends on clinical symptoms and other laboratory findings.
Sample Type
- A venous blood sample is collected.
- Blood is mixed with an anticoagulant.
- The tube is kept vertical for one hour.
- The distance RBCs settle (in mm) indicates ESR.
Test Preparation
- No fasting required.
- Avoid vigorous exercise before the test.
- Inform your doctor about:
- Pregnancy
- Anemia
- Recent infections
- Any medications (steroids, NSAIDs may affect ESR)
- Wear loose clothing for easy blood collection.
When to Consult a Doctor
See a doctor if:
- Your ESR is significantly high without any known reason.
- You have persistent fever, fatigue, or joint pain.
- You experience weight loss or night sweats.
- Symptoms of autoimmune disease appear.
- If you have headache + vision problems (temporal arteritis risk).
- ESR continues to rise despite treatment.
Seek urgent medical care if:
- Severe headaches with vision loss
- High fever with breathing difficulty
- Chest pain or severe fatigue
Important Word Explanations
- Erythrocytes: Red blood cells.
- Inflammation: Body’s response to injury or infection.
- Fibrinogen: Protein that increases ESR during inflammation.
- Autoimmune disease: The immune system attacks the body.
- CRP: Another inflammation test, often paired with ESR.
- Sedimentation: Settling of particles in a liquid.
- Temporal arteritis: An inflammation of arteries in the head.
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