Introduction to haematology

Question 1

Haemopoiesis

Answer 1

physiological development process that gives rise to the cellular components of blood

Question 2

Symmetric self-renewal

Answer 2

Resting stem cell; rely on them in the times of stress e.g. in injury

Question 3

Asymmetric self-renewal

Answer 3

giving rise to a differentiated cell and a stem cell – maintains stem cell pool

Question 4

What are the 2 blood lineages

Answer 4

• myeloid and lymphoid

Question 5

Erythrocytes

Answer 5

• 120 day lifespan
• haemoglobin for oxygen
• Low red cells = anaemia
• High RC = polycythaemia

Question 6

Relative polycythaemia

Answer 6

plasma volume is reduced but cell number stays same. RBC are suspended in plasma = increased proportion

Question 7

Leukocytes (WBCs)

Answer 7

• Immunity and host defence

- Granulocytes - have cytoplasmic granules

Question 8

Neutrophils

Answer 8

• Phagocytes
• Most common white cell -fairly short lived
• Lobed nucleus - can be reduced in myelodysplasia and in other malignant diseases. Lobes can increase = hypersegmented – seen in b12 anaemia or folic acid deficient
• Increased numbers = neutrophilia = seen in infection; particularly bacterial. Decreased numbers = neutropenia = seen in response to chemo/side effect of drugs

Question 9

• Eosinophils

Answer 9

• Nucleus is bilobed and granules are orange/red
• Fights parasitic infections and allergies
• Increased numbers = eosinophilia - occurs during use of aspirin

Question 10

• Basophils

Answer 10

• Rare cells – dark heavily granulated cells
• Found in CML (chronic myeloid leukaemia)
• Increased numbers = basophilia

Question 11

Monocytes

Answer 11

• Phagocytic and antigen presenting cells
• Can migrate to tissues and are then identified as macrophages or histiocytes
• Increased numbers = monocytosis caused by diseases like TB

Question 12

Platelets

Answer 12

• Derived from bone marrow megakaryocytes (have many nuclei)

- form part of the blood clotting system, Aggregate to plug holes in damaged blood vessels

Question 13

Lymphocytes

Answer 13

• Increased numbers = lymphocytosis – e.g. atypical in glandular fever, CLL (accumulation of mature looking lymphocytes)
• Decreased numbers = lymphopenia – e.g. in bone marrow transplant and infection

Question 14

Natural killer cells

Answer 14

• Innate immune system – don’t rely on human leukocyte antigen system
• Larger granular lymphocytes
• Recognise “non-self”

Question 15

T lymphocytes

Answer 15

• Adaptive immune system – dependent on HLA system
• Multiple sub-types
• Involved in cell-mediated immunity
• Interact with B cells and macrophages- Regulate immune responses

Question 16

B lymphocytes

Answer 16

• Adaptive immune system
• Rearrange IG genes to enable antigen specific antibody production
• Humoral immunity – make antibodies
• Increase numbers of plasma cells = plasmacytosis

Question 17

Full Blood Count

Answer 17

• taken in EDTA anticoagulated blood bottle
  Measures:
• Haemoglobin concentration
• Red cell parameters (MCV = mean cell volume and MCH = mean cell haemoglobin content)
• White cell count (WCC)
• Platelet count

Question 18

When interpreting FBC be alert of:

Answer 18

• Technical problems e.g. thrombocytopenia
• Abnormal results
• Serious urgent abnormalities

Question 19

Blood film

Answer 19

• blood on film, get a tail of blood cells that separate to look down microscope

Question 20

Coagulation screen

Answer 20

• Measures time taken for a clot to form when plasma is mixed with specific reagents
• PT = prothrombin time
• APTT = activated partial thromboplastin time
• TT = thrombin time

Question 21

Bone Marrow Aspirate and Trephine

Answer 21

• Aspirate = liquid marrow aspirated from posterior iliac crest – looks at the cells in them
• Trephine = core biopsy is taken to look at bone marrow architecture

Question 22

Anaemias

Answer 22

• Defined as Hb below 130 (male) or 115 (female)

Question 23

Microcytic hypochromic anaemia

Answer 23

• Microcytic = small red cells - MCV < 80
• Hypochromic = low Hb per cell – MCH < 27 – cells look paler than usual
• Causes = iron deficiency, thalassaemia, chronic disease

Question 24

Normocytic normochromic anaemia

Answer 24

• Normal cell size and normal Hb per cell – MCV = 80-95, MCH > 27
• Causes = haemolytic anaemia, chronic disease, acute blood loss, bone marrow failure

Question 25

Macrocytic anaemia

Answer 25

• MCV > 95 but normal Hb per cell = MCH > 27
  2 types:
• Megaloblastic = inadequate development of nucleus – causes = vitamin B12 deficiency or folate deficiency
• Non-megaloblastic = big cells but no nuclear dysmorphia - causes = alcohol, myelodysplasia

Question 26

Sickle cell =

Answer 26

associated with haemolysis and thrombosis