Erythrocyte Sedimentation Rate


Properties of Red Blood Cells – Rouleaux Formation Definition, Erythrocyte Sedimentation Rate (ESR) Automated Normal Range Test Presentation for Biology / Medical Students  

PROPERTIES OF RED BLOOD CELLS
1: ROULEAUX FORMATION When blood is taken out of the blood vessel, the red blood cells pile up one above another like the pile of coins. This property of the red blood cells is called rouleaux (pleural = rouleau) formation. If blood is mixed suitably with an anticoagulant (sodium citrate in the popular Westergren method) and allowed to stand vertically in a special tube (e.g. Westergren tube), the erythrocy­tes, because they have a higher specific gravity than plasma, begin to settle down, leaving a clear supernatant plasma above. The length of the column of this clear supernatant plasma in mm after the end of first hour is the erythrocyte sedimentation rate (ESR). The tendency of the RBCs to settle down increases when they form rouleaux.. In rouleaux, RBCs pile one over another like a pile of coin .Rouleaux formation increases when there is increase of plasma fibrinogen and y globulin. Most infections, inflam­mations and destructive diseases cause increase of y globu­lins (including fibrinogen). Therefore, ESR increases in most acute as well as in chronic' infections, collagenous disease (eg. rheumatoid arthritis), tuberculosis etc. It also increases in cancers. 

ormal values of ESR in male, by the Westergren method, is about 5 mm and in female about 10 mm in the 1st hour. A rise in ESR indicates the presence of infective/ inflammatory / destructive disease but does not help in specific diagnosis. However, ESR values are important for prognosti­cation as well as for assessment of progress in a person under treatment.          

2. SPECIFIC GRAVITY
The specific gravity of red blood cell is 1.092 to 1.101.

3. PACKED CELL VOLUME
When the blood is collected in a centrifuge tube along with proper anticoagulant and centrifuged for a period of 30 minutes at a speed of 3000 rpm (revolutions per minute), the red blood cells settle at the bottom of the tube leaving the clear plasma at the top. The red blood cells form 45% of the total blood. This is called the packed cell volume or hematocrit. The volume of plasma is 55%.

4.SUSPENSION STABILITY
During circulation, the red blood cells remain suspended uniformly in the blood. This property of the red blood cells is called the suspension stability.

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