Erythrocytes sedimentation rate trial

Learn

#Erythrocyte Sedimentation Rate (ESR) in Humans: A Comprehensive Overview

Introduction:-

The Erythrocyte Sedimentation Rate (ESR) also known as the sed rate, is a common hematological test that measures the rate at which red blood cells (erythrocytes) settle at the bottom of a tube over a specified period, usually one hour. This test is a non-specific marker of inflammation and is widely used in clinical practice to detect and monitor inflammatory conditions, infections, autoimmune diseases, and malignancies.

Despite its simplicity, the ESR remains a valuable diagnostic tool due to its sensitivity to changes in plasma proteins, particularly fibrinogen and immunoglobulins, which increase during inflammation. However, because it is non-specific, it is often used alongside other tests like C-reactive protein (CRP) for better diagnostic accuracy.

This article explores the principles, methodology, clinical significance, influencing factors, advantages, limitations, and modern alternatives** to the ESR test.

---

1. Principles of ESr

The ESR is based on Stokes' Law, which describes the sedimentation of particles in a liquid. When anticoagulated blood is placed vertically in a narrow tube, red blood cells gradually settle due to gravity. The rate at which they fall depends on:

-Plasma viscosity– Increased plasma proteins (e.g., fibrinogen, immunoglobulins) promote rouleaux formation (stacking of RBCs), accelerating sedimentation.

- Red blood cell characteristics – Size, shape, and number affect sedimentation.

- External factors – Temperature, tube angle, and anticoagulant used can influence results.

The Westergren method, the gold standard for ESR measurement, involves filling a 200 mm tube with diluted blood and measuring the distance RBCs fall in one hour (mm/hr).

---

2. Methods of Measuring ESR

Several techniques are used to determine ESR, including:

A. Westergren Method (Most Common)

- Procedure: 

Blood is mixed with sodium citrate (anticoagulant) and placed in a Westergren tube. After 1 hour, the distance from the top of the plasma to the top of the RBC layer is recorded.

- Advantages: 

Highly reproducible, standardized, and widely accepted.

- Disadvantages: 

Requires a large blood sample (2 mL) and manual handling.

B. Wintrobe Method

- Uses a shorter tube (100 mm) and undiluted blood.

- Less sensitive than Westergren but useful in pediatric cases due to smaller sample requirements.

C. Automated ESR Analyzers

- Modern machines use photometry or centrifugation for faster results.

- Advantages: 

Faster (20-30 minutes), less manual error.

- Disadvantages: 

Higher cost, requires calibration.

D. Micro-ESR

- Modified for small blood volumes (e.g., neonates).

- Uses capillary tubes instead of traditional methods.

3. Normal ESR Values

ESR varies by age, sex, and physiological conditions:

| Group                |Normal Range (mm/hr) |

|------------------------|--------------------------

| Men < 50 year  | 0–15                     

| Men > 50 years | 0–20                     

| Women < 50 yr| 0–20                     

| Women > 50 yr| 0–30                     

| Newborns         | 0–2                      

| Children            | 3–13                     

|Pregnant women| May increase up to 40–50  |

---

4. Clinical Significance of ESR

A. Elevated ESR (High Sed Rate)

An increased ESR suggests underlying inflammation and is seen in:

1. Infections(bacterial, viral, tuberculosis)

2. Autoimmune diseases (rheumatoid arthritis, lupus, vasculitis)

3.Malignancies (lymphoma, multiple myeloma)

4.Chronic inflammatory conditions (inflammatory bowel disease)

5. Tissue damage (myocardial infarction, trauma)

6. Anemia(due to altered RBC mass)

7. Kidney disease(nephrotic syndrome)

B. Low ESR (Low Sed Rate)

A very low ESR is less common but may occur in:

1. Polycythemia (increased RBC count slows sedimentation)

2. Sickle cell anemia (abnormal RBC shape reduces rouleaux formation)

3.Hypofibrinogenemia (decreased fibrinogen levels)

4.Congestive heart failure (due to altered blood viscosity)

-5. Factors Affecting ESR

Several variables can influence ESR results:

A. Physiological Factors

- Age: ESR increases with age.

- Sex: Women typically have higher ESR than men.

- Pregnancy: ESR rises due to increased fibrinogen.

- Menstruation: Slight elevation possible.

B. Pathological Factors

- Inflammation: Major cause of high ESR.

- Anemia: Faster sedimentation due to fewer RBCs.

- Hyperviscosity syndromes: Slows ESR.

 C. Technical Factors

- Tube tilt: Increases sedimentation rate.

- Temperature: High temperatures may falsely elevate ESR.

- Anticoagulant: Improper mixing can affect results.

-6. Advantages of ESR Testing

- Simple and inexpensive – Widely available in most labs.

- Non-specific but sensitive – Useful for screening inflammation.

- Long-established use– Validated in various diseases.

---

7. Limitations of ESR

- Non-specific – Cannot diagnose a specific disease.

- Slow response– Takes 24–48 hours to rise after inflammation starts.

- Affected by multiple factors (e.g., anemia, age, sex).

- Less sensitive than CRP in acute inflammation.

8. ESR vs. C-Reactive Protein (CRP)

While both indicate inflammation, CRp is often preferred because:

- Rises faster(within 6–12 hours of inflammation).

- Returns to normal quicker after resolution.

- Less affected by non-inflammatory conditions (e.g., anemia).

However, ESR remains useful in chronic conditions like rheumatoid arthritis and temporal arteritis.

9. Modern Alternatives to ESR

- **CRP (C-Reactive Protein)** – More specific for acute inflammation.

- Procalcitonin – Used for bacterial infections.

- Plasma viscosity testing – Alternative in some labs.

- Automated hematology analyzers – Provide faster ESR approximations.

-10. Conclusion

The Erythrocyte Sedimentation Rate (ESR) is a time-tested, simple, and cost-effective test for detecting inflammation. Despite its non-specific nature, it remains valuable in diagnosing and monitoring chronic inflammatory diseases, infections, and malignancies. However, due to its limitations, it is often used alongside CRP and other biomarkers for better diagnostic accuracy.

With advancements in laboratory technology, automated ESR analyzers and alternative inflammatory markers are gaining popularity. Nevertheless, the ESR continues to hold clinical relevance, particularly in resource-limited settings and for monitoring disease progression in chronic conditions.