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1.2.5 Anatomy, Physiology, and Health Education I Laboratory

ESR

Lab 3. Determination of Erythrocyte Sedimentation Rate by Westergren's Method

Developed by Prova Biswas

Working principle

The distance(mm),the erythrocyte falls during placing the anticoagulated blood in the ESR tube in a vertical position, is measured after a certain time (1/2 hour).

Theory

When anticoagulated blood is allowed to stand undisturbed for a period of time, the erythrocytes tend to sink to the bottom. Two layers are formed, the upper plasma layer and the lower one of red blood cells. The rate at which the red cells fall is known as the erythrocyte sedimentation rate. The first is the stage of aggregation when the red cells form rouleaux (RBCs cling together like coins in pile). This is followed by the stage of sedimentation in which the falling of the red cells takes place. The rate of falling of erythrocyte is directly proportional to the aggregation in first stage.

Clinical significance

ESR is increased in all conditions where there is tissue breakdown or where there is entry of foreign proteins in the blood, except for localized mild infections. The determination is useful to check the progress of the infectious disease. If the patient is improving the ESR tends to fall. If the patient's condition is getting worse the ESR tends to rise. The ESR increases high in some chronic bacterial diseases like tuberculosis, typhoid, rheumatic diseases etc.

Normal range

Male: 0-15 mm after 1st hour.

Female: 0-20 mm after 1st hour.

Factors affecting ESR

i. The changed levels of plasma proteins such as fibrinogen and globulins tend to increase rouleaux formation. ESR is therefore increased in any condition causing an increase in fibrinogen (any cause of tissue breakdown such as tuberculosis and other chronic infections) or globulins (rheumatic fever, myeloma, kala-azar, etc.)

ii. Albumin retards sedimentation.

iii. High blood count however, tend to lower the sedimentation rate, while low blood counts tend to accelerate the rate of fall.

iv. ESR is greater in women than in men.

v. During pregnancy ESR gradually increases after 3rd month and returns to normal in about 3 to 4 weeks after delivery.

vi. ESR is low in infants and gradually increases up to puberty.

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