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HHAD: Human Disease > Haematology 1 > Flashcards

Haematology 1 Flashcards

1
Q

What is haematopoiesis?

A

It is the process through which all blood cells are derived

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2
Q

What are the components of the haematopoietic system? (5)

A 
Bone marrow 
Spleen 
Liver
Lymph nodes
Thymus
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3
Q

Where does haematopoiesis occur in:
Children?
Adults?

A

C: bone marrow of nearly all bones
A: axial skeleton (skull, spine, ribs) and proximal parts of the long bones

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4
Q

What type of cell starts the haematopoietic process?

A

Pluripotent stem cell

can self-renew and differentiate

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5
Q

What is the main function of this cell line?

Red blood cells

A

Transport oxygen from lungs to tissues

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6
Q

What is the main function of this cell line?

Neutrophils (3)

A

Chemotaxis
Phagocytosis
Killing phagocytosed cells

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7
Q

What is the main function of this cell line?

Eosinophils (3)

A

Neutrophil functions
Antibody-dependent damage to parasites
Immediate hypersensitivity

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8
Q

What is the main function of this cell line?

Basophils (2)

A

Immediate hypersensitivity

Modulate inflammatory response via proteases and heparin

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9
Q

What is the main function of this cell line?

Monocytes & macrophages (5)

A 
Chemotaxis 
Phagocytosis 
Killing of microorganisms 
Antigen presentation
Release of IL-1 & TNF
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10
Q

What is the main function of this cell line?

Platelets

A

Primary haemostasis (adhere to subendothelial connective tissue)

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11
Q

What is the main function of this cell line?

Lymphocytes

A

Immune response

Haemopoietic growth factors

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12
Q

What is anaemia?

A

It is a reduction in haemoglobin level below reference range for age and sex of individual

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13
Q

What dictates the symptoms and signs of anaemia?

A

The rate at which anaemia develops

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14
Q

Outline the symptoms of anaemia (6)

A 
Lassitude (lack of energy)
Fatigue 
Dyspnoea on exertion (hard to breathe) 
Palpitations 
Headache 
Chest pain
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15
Q

Outline the signs of anaemia (5)

A 
Pallor 
Tachycardia 
Wide pulse pressures (wide difference between top and bottom number) 
Systolic flow murmurs 
Congestive cardiac failure
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16
Q

What are the potential mechanisms in the development of anaemia? (5)

A
  1. Blood loss
  2. Decreased red cell lifespan (haemolytic)
    • Congenital (sickle cell anaemia)
    • Acquired (malaria, drugs)
  3. Impairment of red cell formation
    • Insufficient erythropoiesis
    • Ineffective erythropoiesis
  4. Pooling and destruction in spleen
  5. Increased plasm volume (pregnancy)
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17
Q

Name the 3 ways anaemia can be classified by morphology

A

Microcytic
Normocytic
Macrocytic

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18
Q

What may cause microcytic anaemia? (2)

A

Iron deficiency

Thalassaemia

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19
Q

What may cause normocytic anaemia? (3)

A

Acute blood loss
Anaemia of chronic disease
Chronic renal failure

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20
Q

What may cause macrocytic anaemia? (4)

A

Alcoholism
Folate deficiency
Vitamin B12 deficiency
Drugs

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21
Q

What is the most common cause of anaemia worldwide?

A

Iron deficiency anaemia

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22
Q

Why does the body tightly control absorption of iron?

A

Because excess iron is potentially toxic

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23
Q

What are the 3 mechanisms from which iron deficiency anaemia (IDA) can develop?

A
  1. Poor dietary intake (e.g. vegetarians, vegans)
  2. Malabsorption (duodenum in coeliac disease or jejunum in Crohn’s disease)
  3. Increased loss (commonly menorrhagia (menstrual) or GI)
    (e. g. IBS, peptic ulceration, malignancy, hookworm)
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24
Q

Outline classic presentation of IDA (6)

A

Koilonychia (spoon nails)
Angular cheilitis
Atrophic glossitis (smooth, painful tongue)
Recurrent oral ulceration
Burning mouth
Oesophageal web (Plummer-Vinson/Patterson-Brown Kelly syndrome)

[Mild deficiency is typically asymptomatic]

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25
Q

Which demographics are more likely to have IDA? (2)

A

Men
Post-menopausal women

(unexplained)

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26
Q

What investigations are involved when diagnosing IDA? (2)

A

Blood film

Iron studies

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27
Q

What is the treatment for IDA? (4)

A 
Address underlying cause 
Oral supplementation (ferrous sulphate 200mg x 3/day for 3 months) 
Parenteral (taking medication in a way other than via the GI tract) available (fever, arthropathy (joint disease), anaphylaxis)
Blood transfusion (only in severe compromise)
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28
Q

What conditions are associated with normocytic anaemia? (4)

A

Chronic inflammatory/connective tissue conditions (rheumatoid arthritis)
Chronic infections (tuberculosis)
Chronic renal disease (due to reduction in erythropoietin)
Malignancies (bone marrow infiltration)

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29
Q

What are the 2 divisions of macrocytic anaemia?

A
  1. Megaloblastic erythropoiesis (abnormal red cell development due to disordered DNA synthesis)
  2. Normoblastic erythropoiesis (normal red cell maturation)

(to do with production of RBC)

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30
Q

Why is folate essential for the human body?

How does the body obtain folate?

A

It is essential for DNA synthesis

Derived from many food sources (esp green leafy veg)

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31
Q

What are the causes of megaloblastic anaemia (folate)? (5)

A
  1. Inadequate intake (elderly, alcoholism)
  2. Malabsorption (coeliac disease, crohn’s disease, resection)
  3. Increased requirement (pregnancy, haemolytic anaemias, myelofibrosis)
  4. Increased loss (dialysis, liver disease, congestive heart failure)
  5. Drugs (methotrexate, phenytoin, trimethoprim)
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32
Q

Why is vitamin B12 required by the body?

How do humans obtain B12?

A

Required in number of enzymatic reactions - deficiency impacts DNA synthesis
Found only in foods of animal origin

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33
Q

What are the causes of vitamin B12 deficiency? (5)

A
  1. Inadequate intake
  2. Inadequate secretion of intrinsic factor (pernicious anaemia, gastrectomy)
  3. Inadequate release from food (gastritis, PPI, EtOH abuse)
  4. Diversion of dietary B12 (bacterial overgrowth, small intestinal structures)
  5. Malabsorption (Crohn’s disease, ileal resection)
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34
Q

Outline the clinical features of folate and B12 deficiency (4)

A

Generic symptoms and signs of anaemia
Occasionally mild jaundice
Glossitis
Oral ulceration

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35
Q

What are the further clinical features of B12 deficiency exclusively? (3)

A

Peripheral neuropathy (loss of proprioception and vibration sense)
Demyelination with subacute combined degeneration of spinal cord
Dementia

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36
Q

What investigations are done for folate/B12 deficiency?

A

Blood film

Serum folate and B12 (low B12 can lead to low folate - always test together)

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37
Q

What is the treatment for folate/B12 anaemia? (3)

A

Address underlying cause
Oral supplementation (never folate only if B12 level not known)
Parenteral vitamin B12 (IM) required in pernicious anaemia

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38
Q

What are the potential causes of normoblastic anaemia? (4)

A

Alcohol excess
Liver dysfunction
Hypothyroidism
Drugs (methotrexate, azathioprine)

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39
Q

What are the 3 different defects that can cause congenital haemolytic anaemia?

A
  1. Membrane defects
    - number of proteins are essential to maintain membrane integrity; any mutation can lead to increased fragility and haemolysis.
  2. Enzyme defects
  3. Globin defects
40
Q

What is the most common congenital haemolytic anaemia condition?

A

Hereditary spherocytosis (RBC shaped like spheres)

41
Q

Give an example of an enzyme defect that can result in congenital haemolytic anaemia?
How does it lead to anaemia?

A

Glucose-6-phosphate dehydrogenase (G6DP) Deficiency
This is involved in glucose metabolism
Deficiency results in increased sensitivity to oxidative stress

42
Q

What are the 2 types of acquired haemolytic anaemia?

A

Immune

Non-immune

43
Q

How is phagocytosis triggered in immune acquired haemolytic anaemia?

A

IgG coated red blood cells interact with macrophages resulting in phagocytosis

44
Q

Name an example of an autoimmune process that may be included in acquired immune haemolytic anaemia? (5)

A 
Idiopathic 
Secondary to infection 
drugs
SLE
haematological malignancies
45
Q

How may acquired haemolytic anaemia be cause by alloimmune results?

A

Transfusion and production of antibodies to transfused red cell

46
Q

What may cause acquired non-immune haemolytic anaemia? (4)

A

Trauma
Burns
Infection (e.g. malaria)
Drugs (dapsone - often used for skin conditions like dermatitis)

47
Q

Clinical features of haemolytic anaemia vary greatly depending on cause. What are the common features? (4)

A

Pallor
Jaundice (due to elevated bilirubin)
Splenomegaly
Expansion of erythropoiesis leading to bone deformities (frontal bossing) and pathological fractures

48
Q

What does normal Hb comprise of?

A

2 alpha chains
2 beta chains

Each globin group is associated with a haem group (protoporphyrin ring and iron)

49
Q

What happens to Hb between O2 bound and unbound states?

A

It undergoes a conformational change

50
Q

Does Hb always have the same affinity for oxygen?

A

No - it’s affinity alters (loads oxygen in high oxygen tension environments and releases oxygen in low oxygen environments)

51
Q

What are the 2 main groups of thalassaemia and what does this indicate?

A

a-thalassaemia (alpha chain defect)

b-thalassaemia (beta chain defect)

52
Q

What is the consequence of the excess chains in thalassaemia?

A

Excess chains precipitate in precursor red cells, this leads to premature death.
Precipitated chains also result in oxidative damage to the cell membrane leading to haemolysis

53
Q

Severity of thalassaemia depends on what?

A

The degree of globin chain imbalance

54
Q

How is thalassaemia diagnosed?

A

It is made by using Hb electrophoresis

55
Q

Which type of thalassaemia is most common is SE Asia (thailand, indonesia) and west africa?

What is the prevalence of this?

A

Alpha thalassaemia

20-30%

56
Q

How many alpha-globin genes are there on 2 chromosomes?

A

4

57
Q

Name the 4 traits/diseases of alpha thalassaemia?

A

a+ thalassaemia trait (deletion of 1 gene) - asymptomatic with normal Hb and reduced MCV

a0 thalassaemia trait (deletion of 2 genes on 1 chromosome) - slight reduction Hb and reduced MCV

Hb H disease (deletion of 3 genes) - chronic haemolytic anaemia (transfusion independent)

Hb Bart’s hydrops fetalis syndrome (deletion of all 4 genes) - intrauterine or neonatal death

58
Q

What causes a+ thalassaemia and what are the consequences of this?

A

Deletion of 1 gene

Asymptomatic with normal Hb
Reduced MCV

59
Q

What causes a0 thalassaemia and what are the consequences of this?

A

Deletion of 2 genes on 1 chromosome

Slight reduction Hb
Reduced MCV

60
Q

What causes Hb H disease (a-thalassaemia) and what are the consequences of this?

A

Deletion of 3 genes

Chronic haemolytic anaemia
transfusion independent

61
Q

What causes Hb Barts hydrops fetalis syndrome (a-thalassaemia) and what are the consequences of this?

A

Deletion of all 4 genes

Intrauterine or neonatal death

62
Q

Which type of thalassaemia is more common in Southern Europe (especially Greece)?

What percentage of the world population are beta-thalassaemia carriers?

A

Beta-thalassaemia

~1.5% are carriers

63
Q

Which type of thalassaemia is usually due to mutation rather than deletion?

A

Beta thalassaemia

64
Q

Outline the 2 types of beta-thalassaemia

A

Heterozygous b-thalassaemia trait - asymptomatic

Homozygous b-thal - moderate to marked anaemia developing within first 2 years (may be transfusion dependent)

65
Q

Name the 4 clinical classifications of thalassaemia

A

Thalassaemia minima
Thalassaemia Minor
Thalassaemia intermedia
Thalassaemia major

66
Q

When does Thalassaemia minima occur?

A

When there is a mutation presence but there isn’t clinical consequence

67
Q

What are the consequences of thalassaemia minor?

A

Microcytosis

Hypochromic red cells

68
Q

What are the consequences of thalassaemia intermedia?

A

Microcytic hypochromic anaemia

Extramedullary haematopoiesis with splenomegaly

69
Q

What are the consequences of thalassaemia major?

A

Microcytic hypochromic anaemia
Extramedullary haematopoiesis with splenomegaly
Severe anaemia and transfusion dependent

70
Q

Describe the clinical presentation of thalassaemia (4)

A

Typically those of anaemia unless severe

Untreated = growth retardation, splenomegaly, bony deformities (due to marrow expansion due to trying to compensate for chronic anaemia)

Oral: enlargement of maxilla (chipmunk facies), migration and spacing of upper anterior teeth

Iron overload - due to transfusion leading to iron accumulation in myocardium (cardiac failure), liver (cirrhosis), pancreas (DM) and salivary glands

71
Q

What is the most common structural variant of Hb? What causes this variation?

A

HbS

Due to mutation in B-globin gene. Interaction of sickle B-globin chains with normal a-globin chains

72
Q

What does HbS variant result in?

A

Deformation of cell into sickle shape

73
Q

Where is HbS most prevalent?

A

Tropical Africa, middle east and southern india

Areas in which falciparum malaria is endemic

74
Q

What percentage of Hb is HbS in heterozygous sickle cell trait (carrier)?

A

20-40%

usually asymptomatic

75
Q

What percentage of Hb is HbS in sickle cell anaemia (homozygous)?

A

100%

76
Q

What are the clinical manifestations of sickle cell anaemia?

A 
Chronic haemolytic anaemia 
Hyposplenism (due to infarcts = increased risk of infection)
Splenic sequestration 
Acute chest syndrome 
CVA/TIA 
Bone infarction and subsequent infections 
Chronic leg ulcers
Haematuria and chronic renal disease

Sickling = shortened erythrocyte survival, microcirculation obstruction

77
Q

How is sickle cell anaemia diagnosed?

A

Hb electrophoresis

78
Q

How is sickle-cell anaemia managed? (3)

A

Transfusion when necessary
Pneumococcal, haemophilus influenzae type B (Hib) and meningitis vaccinations (increased susceptibility due to hyposplenism)
Prophylactic penicillin

79
Q

Describe a typical crises with sickle cell anaemia

A

Acute vaso-occlusive painful episodes
Precipitated by infection, dehydration, hypoxia
Oral and IV fluids
Analgesics (opiates)

80
Q

What can lead to an immunological reaction between a blood donor and recipient?

A

Variation in surface constituents - e.g. different blood group systems

So compatibility and cross-matching is essential

81
Q

H antigen is attached to cell membrane - what affect does A, B or O allele have on the H antigen?

A

A and B modify H antigen

O = no modification

82
Q

What are the 6 possible ABO genotypes?

A 
AA
AB
AO
BB
BO
OO
83
Q

What are the 4 ABO phenotypes? - so what blood can they receive?

A

A (receive A or O)
AB (receive A, B or O)
B (r B or O)
O (r O)

84
Q

What are the 2 genetic loci that encodes for Rh?

A

RHD and RHCE

2 genetic loci on one chromosome

85
Q

Which antigen is most clinically relevant?

A

D antigen

86
Q

What may happen if a person if RhD-neg received RhD-pos blood transfusion?

A

They are at a significant risk of developing anti-D antibodies after transfusion

87
Q

Why do pregnant women have the Rh status tested?

A

Because if a mother is RhD-neg, the foetus may be RhD-pos and placental transfer may lead to an adverse reaction.
Pregnant mothers are given antenatal anti-D prophylaxis if necessary

88
Q

How can immune-mediated transfusion reactions be classified?

A

Acute reactions (within 24 hrs, include acute haemolytic, febrile non-haemolytic, allergic and transfusion-related acute lung injury)

Delayed reactions (occur days to weeks after, include delayed haemolytic transfusion reactions, transfusion-associated graft vs host (GVHD) disease and post-transfusion purpura)

89
Q

Immune-mediated transfusion reactions have what mortality rate?

A

10%

90
Q

Immune-mediated transfusion reactions - what are the clinical features? (9)

A 
Fever
Agitation/anxiety
Rigor
Rash
Flushing and sweating 
Chest/abdominal pain 
Profound hypotension 
Bleeding 
Diarrhoea
91
Q

Immune-mediated transfusion reactions - what is the management for this? (7)

A
  • Stop transfusion
  • Check patient identity against donor blood product unit
  • Replace giving set
  • Paracetamol
  • IV fluids
  • If suspect anaphylaxis IM Adrenaline
  • Contact haematology
92
Q

What is the dental relevance of anaemia?

A

People may present with oral features suggestive of anaemia

Alternatively anaemia may complicate treatment - if no explanation, may be sensible to delay treatment

93
Q

What oral features may you see that could indicate haematinic deficiencies (ie iron, vitB12, folate)? (4)

A

Angular cheilitis
Glossitis
Oral ulceration
Peripheral neuropathies

94
Q

What oral features may you see in sickle cell anaemia? (4)

A

Oral pain possibly due to infarction
Osteomyelitis
Trigeminal neuropathy (due to osteomyelitis)
Hypomineralised dentition

95
Q

What radiographic features may you see if a pt has anaemia? (3)

A

Dense lamina dura
Hypercementosis (cementum is thickened)
Radio-opacities due to previous infarcts

96
Q

What treatment issues can be caused by anaemia?

A
  1. Bleeding:
    If bone marrow infiltration, may be failure of other cell lines (e.g. platelets) with increased risk of bleeding.
    Liver disease may result in anaemia as well as increased risk of bleeding due to impact on clotting factors synthesis
  2. Anaesthesia
    Avoid prilocaine (methemoglobinemia - increased methemoglobin in blood)
    Thalassaemia and sickle cell anaemia can complicate procedures performed under general anaesthesia

HHAD: Human Disease (20 decks)

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