Hematology Erythrocyte-Sedimentation-Rate.ppt

Notes

1. (ESR)

2. †The Erythrocyte Sedimentation Rate (ESR) is a
nonspecific measurement used to detect and
monitor an inflammatory response to tissue injury
(an acute phase) in which there is a change in the
plasma concentration of several proteins (termed
acute phase proteins).
†This procedure, very simply, consist of allowing a
specific amount of blood to sit in a vertical
position for a period of time (usually one hour).
The distance, in millimeters, that the red cells fall
during this time period is the erythrocyte
sedimentation rate and is reported in mm/hr.
†The ESR is affected by three factors:
† Erythrocytes,
†Plasma composition,
†Mechanical/technical factors.

3. †A factor of chief importance in determining the
distance that the RBCs falls is the size or mass of
the falling particle. The larger the particle, the
faster its rate of fall.
†In normal blood, the RBCs remain more or less
separated. They are negatively charged and,
therefore repel each other.
†In certain diseases, however, plasma protein
concentration may be altered, causing a reduction
in the negative charge of the RBCs and consequent
formation of rouleaux. This leads to a larger mass
and an increased sedimentation velocity.
†Agglutination of RBCs due to change in the
erythrocyte surface also leads to an increased RBC
mass and a more rapid sedimentation rate.

4. †Macrocytes tend to settle more rapidly than
microcytes.
†Anisocytosis and poikilocytosis reduce the ability of
RBCs to form large aggregates and there by tend to
falsely lower ESR.
RBCs show an alteration in shape, such as sickle cells
and spherocytes, are unable to aggregate or form
rouleaux and the sedimentation rate is decreased.
†In severe anemia, the ESR is markedly elevated.
The concentration of RBCs is decreased, aggregation
and rouleaux formation are increased, and they
therefore, settle out more easily and rapidly.
†In polycythemia, in which the RBCs count is high, the
ESR is generally normal.

5. †The plasma composition is the most important
factor determining the ESR. Rouleaux and
aggregation of the RBCs are controlled
primarily by the levels of acute phase proteins
(most notable fibrinogen, -1 globulin, and -2
globulin); increasing these three plasma
protein levels are increased in the plasma.
†As the concentration of protein increases so
does the viscosity of the plasma. Although an
increased plasma viscosity will tend to inhibit
the fall of the RBCs, the increase in plasma
proteins are generally those which cause
rouleaux and aggregation of the RBCs, which
affects the ESR more greatly than does the
increased plasma viscosity. Increased
concentrations of albumin will tend to lower
the ESR.

6. †It is important that the ESR tube be exactly
perpendicular. A tilt of 3
0
can cause errors up to
30%.
†Also, the rack holding the tubes should not be
subject to any movement or vibration.
†Minor, everyday variations in room temperature
do not significantly affect the ESR. With large
changes in temperature, however, the
sedimentation rate increases as the temperature
increases.
†The length and inner diameter of the ESR tube
also affect the final test results. ESR tubes with a
narrower than standard bore will generally yield
lower sedimentation rates.

7. †The ESR represents a nonspecific response
to tissue damage and inflammation and
denotes the presence of disease, but not its
severity.
†It primarily reflects changes in the plasma
proteins that accompany most the acute
and chronic infections, tumors, and
degenerative diseases. It may be used to
follow the progress of certain diseases such
as tuberculosis and rheumatoid arthritis.

8. 1.Pregnancy (after the
third month).
2.Acute and chronic
infections.
3.Rheumatic fever.
4.Rheumatoid arthritis.
5.Myocardial infection.
6.Nephrosis.
7.Acute
hepatitis.
8.Menstruation.
9.Tuberculosis.
10.Hypothyroidis
m.
11.Hyperthyroidi
sm.Adults over 60 years of age frequently
have a slightly higher ESR value due
primarily to decreased concentrations of
plasma albumin.

9. 1.Polycythemia.
2.Congestive heart failure.
3.Hypo-fibrinogenemia.
4.The presence of red blood cell
abnormalities (poikilocytosis,
spherocytes, and sickle cells).

10. Drugs such as dextran, methyldopa
(Aldomet), oral contraceptives,
penicillamine procainamide,
theophylline, and vitamin A can
increase ESR, while aspirin, cortisone,
and quinine may decrease it.

11. †Whole blood (4 volumes) anti-coagulated with 0.109M
tri-sodium citrate (1 volume), or EDTA anti-coagulated
blood (4 volumes) diluted with 0.85% sodium chloride
(1 volume) is mixed, placed in a Westergren pipette,
and allowed to stand for exactly 1 hour in a vertical
position. The number of millimeters the red blood
cells fall during this timed period constitutes the ESR.
†The normal values for the modified Westergren ESR
are
0 to 20mm/hour for women,
0 to 15mm/hour for men,
0 to 10mm/hour for children.

12. Length = 300.5mm (+/-0.5mm) (in
order to fit into standard racks)
External diameter = 5.5mm (+/-
0.5mm)
Internal bore = 2.65mm (=/-
0.15mm)
Graduated scale on pipette =
200mm (+/- 0.35mm) (Graduated
lines of uniform thickness 0.2mm)
1.Disposable Westergren pipette calibrated in
millimeters.
The National Committee for clinical laboratory
standards has set specific dimensions for the
pipettes to be used:
2.Westergren pipette rack. All racks should
contain a leveling bulb in order to ensure that
the position of tubes is vertical (+/-2o).
3.Leveling plate for holding the Westergren
rack
4.Timer.

13. †Whole blood (4 volumes) diluted with 0.109
M tri-sodium citrate (1 volume). Alternatively,
3ml whole blood anti-coagulated with EDTA.
(If this specimen type is used the whole
blood [2.0ml] must be diluted with 0.85% w/v
sodium chloride [0.5ml] prior testing).

14. 1.Mix the diluted blood for at least 2 minutes on a
rotator. (The blood should be at room temperature).
Check the tube for clots using two applicator sticks.
2.Make certain the Westergren ESR rack is exactly
level.
3.Fill the Westergren pipette to exactly the 0 mark.
Making certain there are no air bubbles in the blood.
4.Place the pipette in the rack. Be certain the pipette
fits snugly and evenly into the grooves provided.
5.Allow the pipette to stand for exactly 60 minutes.
6.At the end of 60 minutes records the number of
millimeters the red blood cells have fallen. This
result is the erythrocyte sedimentation rate in
millimeters/hour

15. 1.The sedimentation of red blood cells takes
place in three stages:
In the first 10 minutes (Lag Phase) rouleaux
formation occurs and the sedimentation rate is
slight.
Sedimentation then occurs for a period of
approximately 40 minutes at a more rapid and
constant rate (Decantation).
During the last 10 minutes, the sedimentation
rate is slow because of the accumulation of RBCs
in bottom of the tube. The longer the tube the
longer the stage two will last, and therefore the
higher the ESR result (Stationary).

16. 2.Although care may be taken in filling the
sedimentation tube to the 0 mark, occasionally the
upper level of the blood may only reach the 1 or 2
mm mark. In such case, care should be taken
when making the final reading. Subtract the 1 or 2
mm from the final result.
For example,
If the ESR tube is filled to the 2 mm mark and the RBCs
fall to the 18mm mark, the ESR is reported as
16mm/hour.
If the level of blood falls below the 5 mm mark, the test
should be repeated to ensure that valid results are
obtained.
If the upper level of the blood is below 0 due to
leakage of the blood from the bottom of the tube
(Westergren method) the test must be repeated from
step 1. leakage of blood from the bottom of the tube
invalidates the test result.
3.All the sedimentation racks should be equipped
with leveling screws and a spirit level.

17. 4.Mechanical sources of error:
A.If the concentration of EDTA is greater than
recommended, the ESR will be falsely low as a result of
inhibiting rouleaux.
B.The anticoagulants sodium or potassium oxalate and
heparin cause the RBCs to shrink and the ESR will be
falsely high.
C.If the ESR stands for more than 60 minutes, the results
will be falsely elevated. If the test is timed for less
than 60 minutes, invalidly low values are obtained.
D.A marked increase (or decrease) in room temperature
leads to increased (or decreased) ESR result.
E.Tilting of the ESR tube increases the ESR.
F.Bubbles in blood cause invalid results.
G.Fibrin clots present in the blood invalidate the test
results.
5.The ESR should be set up within 2 hours of
blood collection. If EDTA is used as the
anticoagulant, the test may be set up within
6 hours if the blood has been refrigerated.