ESR

Erythrocyte Sedimentation Rate (ESR)

The Erythrocyte Sedimentation Rate (ESR) test measures how quickly red blood cells (erythrocytes) settle at the bottom of a blood sample. ESR is often used to assess inflammation in the body. Here’s a closer look at ESR, how it works, and how it compares to another important marker of inflammation, C-reactive protein (CRP).

 

Key Points About ESR

1. What is ESR? 

ESR is a test that indirectly assesses inflammation by measuring the rate at which red blood cells fall to the bottom of a test tube. When inflammation is present, red blood cells tend to settle faster due to changes in plasma proteins.

 

2. How Does ESR Work? 

• Normal State: Red blood cells carry a negative charge on their surface, which normally causes them to repel each other.
• Plasma Proteins and Aggregation: When inflammation occurs, the levels of certain positively charged plasma proteins, like fibrinogen, increase. These proteins neutralize the red blood cells' charge, allowing them to clump together and form stacks called rouleaux.
• Sedimentation: These rouleaux are denser and sink faster in the blood sample, leading to an increased ESR.

 

3. Causes of Increased ESR 

• Acute Inflammation: Conditions such as infections or autoimmune diseases raise plasma protein levels, which increase ESR. In these cases, CRP levels are often elevated as well.
• Other Factors: High levels of immunoglobulins (antibodies) can increase ESR even if CRP levels remain low. Additionally, abnormalities in red blood cell shape, as seen in disorders like sickle cell anemia, may lower ESR.

ESR increases in diseases such as the following conditions:

1. Tuberculosis
2. All types of anemia except sickle cell anemia
3. Malignant tumors
4. Rheumatoid arthritis
5. Rheumatic fever
6. Liver diseases.

ESR decreases in the following conditions:

1. Allergic conditions
2. Sickle cell anemia
3. Peptone shock
4. Polycythemia
5. Severe leukocytosis.

ESR vs. CRP

CRP as a Preferred Marker 

CRP has become a preferred marker over ESR for detecting inflammation because it’s more specific and reacts faster to changes in the body’s inflammatory state. While ESR remains useful in some clinical situations, CRP often provides clearer information about acute inflammation.

 

When to Use Both ESR and CRP 

In some cases, both ESR and CRP are measured together. If there’s a discrepancy between the results, it may signal a need for further testing. This could include analyzing blood counts, examining plasma protein levels, or assessing the shape and characteristics of red blood cells to understand the reason for the difference.

 

 When is ESR Useful?

Although ESR is now less commonly used due to the availability of CRP, it can still be helpful in certain situations, especially when the behavior of red blood cells or plasma protein composition is altered. By taking into account these individual factors, doctors can better interpret ESR results to make informed diagnostic decisions.