Erythrocyte sedimentation rate (ESR) Definition .
[1]. 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.
[2]. If blood is mixed with an anticoagulant and allowed to stand on a vertical tube, the red cells settle down due to gravity with a supernatant layer of clear plasma.
[3]. ESR is also called sedimentation rate, sed rate or Biernacki reaction.
[4]. It was first demonstrated by Edmund Biernacki in 1897.
Determination of ESR .
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| A. Westergren tube: This is used for determining ESR; B. Wintrobe tube: This is used to determine ESR and PCV. |
There are two methods to determine ESR.
1. Westergren method .
2. Wintrobe method .
Westergren method .
[1]. 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.
[2]. 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.
[3]. The ratio of blood and anticoagulant is 4:1.
[4]. The tube is fitted to the stand vertically and left undisturbed.
[5]. The reading is taken at the end of 1 hour.
Wintrobe method .
[1]. Wintrobe tube is used to determine ESR. Wintrobe tube is a short tube opened on only one end .
[2]. It is 110 mm long with 3 mm bore. Wintrobe tube is used for determining ESR and PCV.
[3]. It is marked on both sides. On one side the marking is from 0 to 100 (for ESR) and on other side from 100 to 0 (for PCV).
[4]. About 1 mL of blood is mixed with anticoagulant, ethylenediaminetetraacetic acid (EDTA).
[5]. 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 .
1. In males : 3 to 7 mm in 1 hour
2. In females : 5 to 9 mm in 1 hour
3. Infants : 0 to 2 mm in 1 hour
By Wintrobe Method
1. In males : 0 to 9 mm in 1 hour
2. In females : 0 to 15 mm in 1 hour
3. Infants : 0 to 5 mm in 1 hour
Significance of Determining ESR .
[1]. Erythrocyte sedimentation rate (ESR) is an easy, inexpensive and non-specific test, which helps in diagnosis as well as prognosis.
[2]. It is non-specific because it cannot indicate the exact location or cause of disease. But, it helps to confirm the diagnosis.
[3]. Prognosis means monitoring the course of disease and response of the patient to therapy.
[4]. 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).
Factors affecting ESR .
Factors increasing 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.
3. Increase in Size of RBC .
When the size of RBC increases (macrocyte), ESR also increases.
Factors deceasing ESR .
1. Viscosity of Blood .
Viscosity offers more resistance for settling of RBCs. So when the viscosity of blood increases, the ESR decreases.
2. RBC count .
When RBC count increases, the viscosity of blood is increased and ESR decreases. And when the RBC count decreases, ESR increases .
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