Haematology Practical Flashcards
What are the components of haemoglobin?
Haem (an iron-containing porphyrin)
Globin (protein)
Which molecule is responsible for the red colour of erythrocytes?
Haemoglobin
Role of haemoglobin?
-It forms a reversible bond with oxygen and it is the medium through which oxygen is transported within the body.
How does knowing the haemoglobin value help us?
It help us to know the blood’s oxygen carrying ability and it assist with the diagnosis of anaemia.
How is the haemoglobin content determined?
-By haemolysing the red blood cells and comparing the colour intensity of the haemoglobin solution obtained with that of the standard.
What are the materials used to test for haemoglobin levels? (5)
-Haemoglobinometer with an accompanying blood chamber.
-Hamolysis applicator stick
-Gauze
-Alcohol swab
-Disposable lancet
Three parts of the blood chamber
-Glass base separated by an H-shaped furrow.
-Cover slip
-Metal holder
Why should the blood chambers and the cover slip be kept clean and dry?
Bcs a soiled surface will cause dispersal of light and affect the results.
Why do they wipe the first drop of blood when collecting blood?
To stimulate blood flow (hence get more blood).
How long should the blood be haemolysed?
For about 15-25 seconds
Why is blood haemolysed when testing haemoglobin levels?
In order to break down the membranes of the individual red blood cells and allow the haemoglobin to go into a uniform solution which is transparent.
How do we manipulate the results in patients with Polycythaemia?
The blood must first be diluted 1:1 with water and the results be multiplied by two.
Which material is not discarded in the haemoglobin test?
The blood chamber, together with it’s components, the cover slip and metal holder.
What are the normal values for the haemoglobin levels?
Males: 14-18 g/100ml or g/dL
Females: 12-16 g/100ml or g/dL
What are the causes of error with the haemoglobin test? (4)
-If the blood clotted in the blood chamber.
-If the amount of blood used was not sufficient.
-If the blood was not haemolysed completely.
-If the haemolysis stick was not coated with a haemolysing agent.
What are the materials required for a haematocrit test? (7)?
-Heparinised capillary tube
-Haematocrit centrifuge
-Gauze
-Alcohol swab
-Disposable lancet
-Ruler
-Plasticine
Why shouldn’t you squeeze the blood from the fingertips while filling the heaparinised capillary tube?
It may cause dilution of the blood with the tissue fluid.
How long should you centrifuge for?
5 minutes at 3000 rotations per minute (rpm)
What is the formula for calculating haematocrit?
Haematocrit= Packed cell volume/volume of blood * 100