ERYTHROCYTE SEDIMENTATION RATE
ERYTHROCYTE SEDIMENTATION RATE
To determine the Erythrocyte sedimentation rate (ESR) of the sample of blood.
ESR is measured as the length in millimeters of the clear column of plasma that collects at the top of a vertical column of anticoagulated blood kept undisturbed for one hour.
Westergren’s pipette. Westergren’s stand, cotton
Westergren’s pipette: is a long cylindrical thick glass tube of 300 mm length and 2.5 mm bore diameter. It is open at both ends and is graduated from 0 to 200 in mm scale from top to bottom.
Westergren’s stand: can hold vertically more than one pipette at a time. There is a rubber cushion at the base on which the lower end of the pipette is made to rest. At the upper end there is a screwcap which fix upon the pipette.
The anticoagulant used is sodium citrate of concentration 3.8%. Proportion of anticoagulant to blood is 1:4. Here we use CPD-A solution with blood.
Take anticoagulated blood in a small beaker. A clean dry pipette is taken and its lower end is introduced well below the surface of blood. With the help of a rubber teat attached to the top of the pipette, draw blood into the pipette without any air bubbles. Keep the upper level of blood column exactly at zero mark and fix the pipette vertically on the stand. Keep it undisturbed for one hour and take the reading directly from the pipette at the end of one hour.
Discussion: Normal values-
Males: 1-4 mm/lst Hr. Females : 3-10 mm/lst Hr.
ESR is the rate at which erythrocytes sediment in anticoagulated blood kept undisturbed. RBC5 settle down due to their greater specific gravity than that of plasma.
Factors influencing ESR
1. Rou leaux formation is a very important factor on which ESR depends. When the degree of rouleaux formation is more (the ratio of surface area to mass of RBC is less) ESR is more
Rouleaux formation is influenced by different factors like:-
a. Shape of RBC - Biconcave disc shape favour rouleaux formation
b. Plasma proteins
Albumin reduces rouleaux formation
Fibrinogen favours rouleaux formation
c. Products of tissue destruction and inflammation favour rouleaux formation. The above plasma factors affect rouleaux formation by changing the electrical charges on the red cells.
2. Size of RBC when more, faster sedimentationConditions in which ESR value is increased
1. Physiological conditions like menstruation, pregnancy
2. Pathological conditions
a. Rheumatic fever, rheumatoid arthritis, tuberculosis, malignancy, acute inflammatory diseases. Severe tissue breakdown occurs in the above conditions.
Decrease in ESR value:
1. Physiologically in newborns
Clinical Significance of ESR
In the past, much clinical importance was given to ESR as a diagnostic and prognostic tool in the assessment of several pathological conditions like rheumatic fever, tuberculosis etc. Abnormal ESR value alone is not diagnostic of any disease condition, but with other evidences, it helps in diagnosis. ESR has a more prognostic significance ie it helps in assessing the course taken by a disease in response to treatment eg. tuberculosis, collagen diseases.
1. There should not be any air bubble in the blood column
2. The top level of blood column should exactly correspond to zero level.
3. The pipette should be mounted vertically.
Wintrobes’s method: Here the Wintrobe’s heamatocrit tube is used as in the other method, for determining ESR.
1. Draw and label Westergren’s pipette.
2. Write about other methods for the measurement of ESR.
3. What are the quantities of Blood and anticoagulant taken for ESR estimation in Clinics?