T7-L1: Introduction to Haematology

Question 1

Define Haemopoiesis.

Answer 1

The physiological developmental process that gives rise to cellular components of the blood.

Question 2

Where are the origins of Hamopoiesis?

Answer 2

Hematopoietic stem cells (HSC) develop in the aorta-gonad-mesonephros region, yolk sac and placenta before colonizing the fetal liver and fetal spleen on their migratory route to their final home in the bone marrow (BM). Haemopoiesis starts at day 27 and rapidly expands at day 35. teh cells are found in the liver in week 5. They can continue for longer in pathological extra-medullary hemotopoiesis

Question 3

What are the different haemopoietic lineages?

Answer 3

Myeloid lineage - gives rise to RBC through the erythroblast, myeloblast (which gives rise to basophils, neutrophils and eosphils and monocytes) and megokaryotes which give rise to platelets.

Lymphoid lineage which gives rise to NK cells, T lymphocytes and B lymphocytes.

Question 4

Define polycythaemia.

Answer 4

Increased red cells,

Question 5

What are causes of neutrophilia?

Answer 5

• Inflammation
• Bacterial infection
• Pregnancy
• Necrosis
• Heavy exercise or any stressor
• Smoking
• Drugs

Question 6

Where do we see eosinophilia?

Answer 6

Parasitic Infections and allergies

Question 7

In what condition do we characteristically see basophilia?

Answer 7

Chronic myeloid leukaemia

Question 8

In what condition do we characteristically see monocytosis?

Answer 8

Tuberculosis

Question 9

In what conditions do we characteristically see lymphocytosis and lymphopenia?

Answer 9

Lymphocytosis - Increased numbers e.g. in atypical lymphocytes of glandular fever (such as infective mononucleosis) and chronic lymphoid leukaemia

Lymphopenia - decreased numbers e.g. in post bone marrow transplant

Question 10

How do we define specificity and sensitivity?

Answer 10

Sensitivity = True positives / True positives and false Negatives (all that have the disease)

Specificity - the proportion of normal results correctly classified by the tests = True negatives / True negatives + False Positives

Question 11

How do we classify microcytic hypo chromic anaemia?

Answer 11

MCV (Mean Cell Volume) less than 80 fl and MCH (Mean Cell Haemoglobin) of less than 27 pg.

Causes include:

• Iron deficiency
• Thalassaemia
• Anaemia of chronic disease
• Lead poisoning
• Sideroblastic anaemia - blood disorders in which the body has enough iron but is unable to use it to make hemoglobin

Question 12

How do we classify normocytic and normochromic anaemia?

Answer 12

MCV (Mean Cell Volume) 80-95 fl and MCH (Mean Cell haemoglobin) of more than 27pg

• This is the case for many haemolytic anaemias
• Anaemia of chronic disease
• after acute blood loss
• Renal disease
• Mixed deficiencies
• Bone marrow failure

The RBC are just being cleared too early. The RBC are normal size with a normal haemoglobin content.

Question 13

How do we classify microcytic anaemia?

Answer 13

MCV (Mean Cell Volume) of greater than 95fl

• Megablastic anaemia occurs in a Vitamin B12 or folate deficiency
• Non-megoblastic macrocyclic anaemia causes include alcohol, liver disease, myelodysplasia (causes a drop in RBC), aplastic anaemia etc.

Question 14

What diagnostic tests can we do using a FBC?

Answer 14

• Haemoglobin concentration (Hb)

Red cell parameters
• MCV (mean cell volume)
• MCH (mean cell Hb)
• Reticulocyte Count

• White Cell Count (WCC)
• Platelet Count (Plt)

Question 15

What tests are done on a coagulation screen?

Answer 15

Prothrombin Time, Activated Partial Thromboplastin Time and Thrombin Time and Fibrinogen