Haematology Flashcards
What are the clinical signs of haematological abnormalities?
- Pallor (pale appearance)
- Exercise intolerance
- Bleeding
- Pyrexia
Which laboratory tests are used to help diagnose a haematological abnormality?
- PCV
- Blood counts
- Blood smear evaluation
What sample is ideal for haematology?
Blood in an EDTA tube (anticoagulant)
Give examples of what needs to be avoided when processing a sample
- inadequate mixing of specimen
- clotted specimens
- platelet clumps
- diluted specimens
- fatty specimens
The haematocrit is equal to?
PCV
A full blood count includes … ?
- Total haemoglobin content
- PCV
- RBC count
- Reticulocyte count
- Platelet count
- Total leucocyte count
- Evaluation of a blood smear
What is measured by an erythrogram?
- Total haemoglobin content
- Haematocrit
- RBC count
- RBC indexes
- Reticulocyte count
- Red cell morphology on blood smear
What are 3 causes of anaemia?
- Inadequate production by the bone marrow
- Increased destruction
- Increased loss of blood
What happens during blood loss anaemia?
Acute or chronic
- Proportional loss of all blood cell components
- Initial decrease of blood volume
- Within a few hours there is activation of mechanisms to maintain volaemia
- Influx of water from the extracellular space
- Reduction of haematocrit and total protein
What are the causes of blood loss anaemia?
- Haemorrhage
- Blood sucking parasite
How is acute blood loss compensated?
By bone marrow
- increased erythropoiesis and red cell mass
What follows chronic blood loss?
Iron deficiency
What is haemolysis?
RBC destruction
- can be immune or non-immune mediated
- both have intravascular and extravascular lysis
What are the mediators of extravascular haemolysis?
Macrophages in tissues and haemoglobin is metabolised by macrophages into bilirubin
Which type of haemolysis can produce haemoglobinuria (red urine)?
Intravascular
What are some causes of non-immune mediated haemolytic anaemia?
- ‘poisons’ e.g. onion, garlic, paracetamol in cats
- bacteria
- viruses
- mechanical damage
- osmotic shock
What is non-regenerative anaemia?
Bone marrow fails to respond to decreased oxygen carrying capacity
If there is blood loss and haemolysis is the anaemia regerative?
Yes
What are the signs of non-regenerative anaemia?
- Iron deficiency
- Chronic kidney disease
- Chronic inflammation
- Endocrine disorders
- Primary bone marrow disease
What is the most possible thing to evaluate to confirm regenerative anaemia?
Peripheral blood for the presence of juvenile red blood cells as we would expect their numbers to increase to compensate for the reduced RBC number
High/low levels of RBCs and reticulocytes are indicators of?
Lower RBC = more severe anaemia
High erythrocyte = regenerative
What is the reference interval for reticulocytes?
<60 x10^9/L
More than this = regenerative
Define the following erythrocyte indexes:
- MCV
- MCHC
- MCH
- Mean corpuscular volume = average erythrocyte size
- Mean corpuscular Hb conc = average erythrocyte Hb concentration
- Mean corpuscular Hb = average amount of Hb per cell
Which erythrocyte indexes are used to classify anaemia?
Mean corpuscular volume
Mean corpuscular Hb conc
What are the 3 classes of anaemia?
Microcytic
Normocytic
Macrocytic
What are microcytic anaemias most commonly due to?
Iron deficiency
What are macrocytic anaemias most commonly due to?
Regenerative anaemia
A raised mean corpuscular volume classifies which type of anaemia and why?
Macrocytic anaemia
- Presence of larger cells which are usually juvenile erythrocytes
Microcytic anaemia is classified by which index and why?
Reduced mean corpuscular volume
- production of small erythrocytes, likely due to less haemoglobin available for erythropoiesis caused by iron deficiency
The … and … of cells should be assessed on a blood smear at low power
Also assess the RBC and WBC … at a higher power
Density
Distribution
Morphology
What are the 2 most common distribution abnormalities seen on a blood smear?
- Agglutination
- Rouleaux formation
What is rouleaux formation?
Stacking of RBCs due to increased plasma proteins coating RBCs
Can be caused by inflammation, cancer
What is agglutination?
Antibody mediated ‘clumping’
Agglutination is strongly supportive of which anaemia type?
Immune mediated haemolytic anaemia
What is the general term for am abnormal shape?
Poikilocytosis
What are two artefactual errors in blood smears?
Delay in making smears
Drying artefact in thick smears
