Erythrocyte Sedimentation Rate

Erythrocyte Sedimentation Rate

✔️DEFINITION

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 a vertical 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

1-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.

2-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 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). 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

VARIATIONS OF ESR-

✔️PHYSIOLOGICAL VARIATION

  • Age- ESR is less in children and infants because of more number of RBCs.
  • Sex- It is more in females than in males because of less number of RBCs.
  • Menstruation- The ESR increases during menstruation because of loss of blood and RBCs
  • 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: -

  • Tuberculosis
  • All types of anemia except sickle cell anemia
  • Malignant tumors
  • Rheumatoid arthritis
  • Rheumatic fever
  • Liver diseases.

✔️ESR decreases in the following conditions:

  • Allergic conditions  
  • Sickle cell anemia
  • Peptone shock
  • Polycythemia
  • Severe leukocytosis.

✔️FACTORS AFFECTING 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 Formatio- 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 DECREASING 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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