............. ESR Tests

Erythrocyte Sedimentation Rate (ESR)l

Principle

When red cells are allowed to settle from their plasma, the speed of their fall is known as the sedimentation rate.

It is a measure of the suspension stability of red cells.
It indirectly measures an increase in fibrinogen and serum globulins.
An increase in either of these results in an increased ESR.

Red cells settle out in three stages:

1. Initial period of aggregation:
rouleaux is formed, and sedimentation is relatively slow; lasts about 10 minutes.

2. Fast settling stage:
settling rate is constant; most of the settling occurs at this stage; lasts about 40 minutes.

3. Packing stage:
continues for 10 minutes and longer.

Reagents, Equipment

Wintrobe Method

1. Wintrobe Tubes
2. 9-inch glass Pasteur pipettes
3. Sedimentation Tube rack
4. Patient EDTA specimen
5. Timer

Procedure

Wintrobe Method

1. Blood should be collected in an EDTA anticoagulant and well-mixed before being used.
2. Using a 9-inch Pasteur pipette that will reach the bottom of the tube, slowly fill the tube with blood, avoiding air bubbles in the column.
3. Adjust the meniscus of the specimen to the "0" line at the top of the tube.
4. Place the tube in an upright position in a rack that will maintain the tube in this position.
5. Set a timer for 1 hour.
6. At the end of 1 hour, read the fall of erythrocytes by recording the level of erythrocytes in the tube. The ESR is read on the same side as the "0" on the tube. Reading from the top downward the ESR is read as the fall of cells in mm per 1 hour of time.

Interpretation of Results

Normal values

Adult Males:
0 to 9 mm/hr

Adult Females:
0 to 15 mm/hr

The ESR is not a diagnostic test for any specific disease, but it is a useful supplemental test. It is often used to follow the course of an inflammatory process.

Disease states with increased ESR.

1. Acute infections
2. Cancer
3. Rheumatoid arthritis
4. Multiple myeloma
5. Pregnancy after the third month

Sources of Error

A. General
1. Dirty tubes
2. Air bubbles
3. Clotted specimen
4. Dimensions of tube

B. Increases ESR
1. Tilted tube
2. Increased temperature
3. Anemia
4. Increased fibrinogen
5. Macrocytic RBC's

C. Decreases ESR
1. Excessive anticoagulant
2. Old blood
3. Decreased temperature
4. Presence of abnormally shaped RBC's
5. Polycythemia
6. Microcytic RBC's

D. Various Methods for performing ESR's
1. Wintrobe
2. Westergren
3. ZSR: Zeta Sedimentation Ratio. This method involves spinning capillary tubes in a special centrifuge called a zetafuge.
4. Cutler - micromethod
5. Landau - micromethod

Erythrocyte Sedimentation Rate (ESR)
Westergren Tube Method

Materials Needed:

Westergren tube and reservoir
Gauze squares
Sedimentation rack
Clock

Procedure

1. Thoroughly mix blood specimen.
2. Fill reservoir to mark.
3. Insert Westergren tube gently into blue cap.
4. Gently work tube down to bottom of reservoir. The tube must be inserted all the way to the bottom. Absorb any excess blood with a gauze square.
5. Apply pressure to tube near its entrance to the blue cap to adjust the blood level down to zero.
6. Place tube in stand and record patient's name and position # in stand.
7. Set timer for 1 hour
8. At the end of 1 hour (+ 5 minutes) read how far rbc's have settled and report in mm/hr. Be sure to read from top to bottom and not from the bottom up.