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
What are the normal values for haematocrit?
Males: 42-52%
Females: 37-47%
What are the causes of error in haematocrit test? (3)
-When the plasticine is included in measurements.
-When the capillary tube used was not heparinised.
-When the end of the tube was not sealed properly, causing blood to ooze out when spun.
What substance is used for blood typing of ABO?
Antiserum
Which substance is used for Rh testing?
Anti-D antisera
What are the materials we need for blood typing?
-Antisera
-Toothpicks for mixing
- Slides for determination of blood groups
-Gauze
-Disposable lancet
-Alcohol swab
What are the colours of antisera for the different antibodies?
Anti-A is blue, Anti-B is yellow, Anti-D is transparent.
Why should we wipe with alcohol swab after dropping the blood in each anti-sera segment?
To prevent cross contamination.
Why is the slide rotated side to side after mixing the anti-sera and blood?
To allow agglutination to take place.
When should we then interpret the results?
Within 2 minutes
Which material don’t we discard in blood typing?
The blood group slide
Causes for errors in blood typing (4)
-Wrong anti-serum was used.
-Expired anti-serum was used.
-Time allowed for agglutination was too short or too long.
-Cross contamination occurred.
What is the average relative density for:
1. Whole blood
2. Blood cells
3. Blood plasma
- 1055
- 1070
- 1030
After how long is sedimentation read?
After an hour
What are the factors that influence ESR? (7)
-Rouleaux formation, fibrinogen, immunoglobulins, acute phase proteins, shape of red blood cells, haematocrit, age and gender.
What causes elevated ESR? (5)
-Kidney disease, collagen diseases, cancer infection, after acute blood loss, during anaemia.
Which substance is used as an anticoagulant in ESR?
3,8% of sterile sodium citrate
What are the materials used in ESR? (4)
-Westergren tube
-Westergren stand
-Blood sample
-Sterile 3.8% of sodium citrate
What are the normal values of ESR?
Male:3-7 mm in an hour
Female: 3-12 mm in an hour
What can cause the abnormalities of ESR? (2)
Increased levels can be due to elevated fibrinogen levels as seen during an infection and inflammation.
Decreased levels can be due to polycythaemia or abnormal shape of RBCs, e.g in sickle cell.
What does qualitative measurements of RBCs focus on, and how does quantitative measurements focus on?
Qualitative measurements focus on the shape and size of the cells, some of the abnormalities here include poikilocytosis, microcytosis etc.
While quantitative is about the number of red blood cells, haemoglobin and haematocrit value.
What are the ff terms:
1. MCV
2. MCH
3. MCHC
- The average volume/size of each RBC.
- The amount of haemoglobin in each red blood cell.
- The concentration of haemoglobin in a given volume of packed red blood cells.
Normal values for:
1. MCV
2. MCH
3. MCHC
- M-83-102fl, F-79-99 fl.
- M- 28-35pg, F-26-34 ph.
- 33-35%
What is the formula to calculate MCV?
MCV(fl)= (Haematocrit/100)/ RBC count
What is the formula to calculate MCH?
MCH(pg)= Haemoglobin (g/L) / RBC count
What is the formula to calculate MCHC?
MCHC(%)= Haemoglobin/Haematocrit *100
What does a MCV>102 pg in males mean?
Macrocytic cells
What does a MCH<26 in females mean?
Hypochromic
What does a MCHC value >35% mean?
Spherocytosis
What does a value of MCH>34 in females mean?
Hyperchromic
What causes abnormalities in blood profile? (3)
-Decreased MCV indicates microcytic anaemia.
-Increased MCV indicates macrocytic anaemia.
-Decreases MCH indicates hypochromic anaemia.
