Hemolysing agent and haemorrhagic
disorders
Tahani Al-ShehriMiss
Objective
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To find nature of substance which cause
haemolysis of red blood cells
To carry out some tests used in the investigation
of haemorrhagic disorders
Introduction and principle
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Haemolysing agents
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Hemolysis: The destruction of red blood cells which
leads to the release of hemoglobin from within the red
blood cells into the blood plasma.
Hemolysis =hemo-", blood + "lysis", the disintegration
of cells.
Hemolysis : is often necessary to break down red cells
to release the contents
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(e.g. hemoglobin estimation, erythrocyte free preparations of
leukocytes or platelets )
Example of haemolysing agent
Detergents or Surfactants
Distilled water
How to calculate the osmolarity of the Sol.
O = M ×(no. of dissociation particles )
 Blood plasma is = 0.308 Osmolar
Nacl : M= (0.302 ÷ 2) = 0.154 M of Nacl ( In this conc. The RBC
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neither shrink nor swell. )
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The 0.154 M NaCl Solution is said to be isotonic with
respect to the red blood cell.
Fragility Test
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Fragility : Liability to Break
a test that measures the resistance of erythrocytes to
haemolysis in hypotonic saline solutions;
erythrocytes to be tested are added to varying
concentrations of saline (usually ranging from 0.85 to
0.10% sodium chloride with 0.05% increments), and
beginning and complete haemolysis are measured;
normal erythrocytes show initial haemolysis at
concentrations of 0.40 to 0.45% and complete haemolysis
at 0.35 to 0.40%;
in hereditary spherocytosis the fragility of the
erythrocytes is markedly increased, whereas in
thalassaemia, sickle cell anaemia, and obstructive
jaundice the fragility of the erythrocytes is usually
reduced.
Haemostatic Mechanism
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The haemostatic mechanism :- The Stop of the bleeding
consists of 4 components:
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Vascular system (endothelial cell (EC) lining)
Platelets (number and function)
Plasma proteins (coagulation factors)
Fibrinolytic mechanisms
Bleeding time and coagulation test
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An investigation of the haemostatic mechanism is
required in
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patient who bleed spontaneously
Who show excessive bleeding after trauma or surgery .
Before surgery in :
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any patient who has a history or a family history of abnormal
bleeding
If the surgery is likely to lead to abnormal bleeding
Bleeding time and coagulation test
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The two test measure :
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The interaction of platelet with the blood vessel wall and the
formation of platelet plug .
Bleeding time : /measure of blood capillary function and the
ability of platelet to stick to the vessel wall.
Coagulation time
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5ml of blood is placed in a glass container, kept at
body temperature and observed
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A clot should occur in 4 to 9 minutes
Prolonged = Severe deficiency of any of the coagulation
proteins ( Haemophilia )
Clotting time
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Bleeding time
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The amount of time it takes to form a clot .
Measure the primary phase of homeostasis ( Measure of
blood capillary function and the ability of the platelets to
stick to the vessel wall)
Depend on :
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Quantity + Quality of platelet .
Normal value : 2-7 min
Aspirin cause abnormal bleeding in some normal person