Erythrocyte sedimentation rate (ESR)

Erythrocyte sedimentation rate (ESR) is the rate at which the erythrocytes settle down. Normally, the red blood cells (RBCs) remain suspended uniformly in circulation. This is called suspension stability of RBCs. If blood is mixed with an anticoagulant and allowed to stand on avertical tube, the red cells settle down due to gravity with a supernatant layer of clear plasma. ESR is also called sedimentation rate, sed rate or

Biernacki reaction. It was first demonstrated by Edmund Biernacki in 1897.

DETERMINATION OF ESR

There are two methods to determine ESR.

1. Westergren method

2. Wintrobe method

WESTERGREN METHOD

In this method, Westergren tube is used to determine ESR.

Westergren Tube

The tube is 300 mm long and opened on both ends. It is marked 0 to 200 mm from above downwards.

Westergren tube is used only for determining ESR. 1.6 mL of blood is mixed with 0.4 mL of 3.8% sodium

citrate (anticoagulant) and loaded in the Westergren tube. The ratio of blood and anticoagulant is 4:1. The

tube is fitted to the stand vertically and left undisturbed. The reading is taken at the end of 1 hour. WINTROBE METHOD

In this method, Wintrobe tube is used to determine ESR.

Wintrobe Tube

Wintrobe tube is a short tube opened on only one end. It is 110 mm long with 3 mm bore. Wintrobe

tube is used for determining ESR and PCV. It is marked(for ESR) and on other side from 100 to 0 (for PCV). About 1 mL of blood is mixed with anticoagulant, ethylenediaminetetraacetic acid (EDTA). The blood is loaded in the tube up to ‘0’ mark and the tube is placed on the Wintrobe stand. And, the reading is taken after 1 hour.

NORMAL VALUES OF ESR

By Westergren Method

In males : 3 to 7 mm in 1 hour

In females : 5 to 9 mm in 1 hour

Infants : 0 to 2 mm in 1 hour

By Wintrobe Method

In males : 0 to 9 mm in 1 hour

In females : 0 to 15 mm in 1 hour

Infants : 0 to 5 mm in 1 hour

SIGNIFICANCE OF DETERMINING ESR

Erythrocyte sedimentation rate (ESR) is an easy, inexpensive and non-specific test, which helps in diagnosis as well as prognosis. It is non-specific because it cannot indicate the exact location or cause of disease. But, it helps to confirm the diagnosis. Prognosis means monitoring the course of disease and response of the patient to therapy. Determination of ESR is especially helpful in assessing the progress of patients treated for certain chronic inflammatory disorders such as:

1. Pulmonary tuberculosis

2. Rheumatoid arthritis

3. Polymyalgia rheumatica (inflammatory disease characterized by pain in shoulder and hip)

4. Temporal arteritis (inflammation of arteries of head).

VARIATIONS OF ESR

PHYSIOLOGICAL VARIATION

1. Age: ESR is less in children and infants because of more number of RBCs.

2. Sex: It is more in females than in males because of less number of RBCs.

3. Menstruation: The ESR increases during menstruation because of loss of blood and RBCs

4. Pregnancy: From 3rd month to parturition, ESR increases up to 35 mm in 1 hour because of

hemodilution.

PATHOLOGICAL VARIATION

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 anemia4. Polycythemia

5. Severe leukocytosis.

FACTORS AFFECTING ESR

FACTORS INCREASEING ESR

1. Specific Gravity of RBC

When the specific gravity of the RBC increases, the cells become heavier and sedimentation is fast. So ESR increases.

2. Rouleaux Formation

Rouleaux formation increases the ESR. Globulin and fibrinogen accelerate the rouleaux formation.

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