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Year 3 General > Haematology > Flashcards

Haematology Flashcards

1
Q

Where is EPO secreted?

A

Type 1 glomus cells in the kidney (as well as in renal fibroblasts)

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2
Q

Where are haematopoietic stem cells found?

A

Yellow bone marrow

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3
Q

Outline the normal process of red cell breakdown

A

Cells >120 days old –> elevated methaemoglobin levels are reduced deformability –> trapped in splenic capillaries –> splenic macrophages lyse RBCs –> iron is removed –> remainder (biliverdin - green) is converted to uncojugated bilirubin (by being converted by biliverdin reductase and albumin added) –> travels to liver for conjugation etc.

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4
Q

Where is iron absorbed?

A

Enterocytes in the duodenum

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5
Q

What factors enhance the absorption of iron?

A

Haem form, Fe2+ form, acidic pH (aids release of iron from transferrin), pregnancy, hypoxia, iron-deficiency

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6
Q

What factors inhibit the absorption of iron?

A

Non-haem form, Fe3+ iron, alkali pH (e.g. with PPIs –> reduced release from transferrin), inflammatory disorders of small intestine, iron overload

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7
Q

Besides iron-deficiency, what else may cause a microcytic anaemia?

A

Thalassaemia or anaemia of chronic disease

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8
Q

What is the main cause of macrocytic anaemia?

A

Vitamin B12/folate deficiency (pernicious anaemia)

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9
Q

Describe how vitamin B12 is absorbed

A

Vitamin B12 is originally bound to proteins in food; this bond is broken by stomach acid –> free B12 then binds to intrinsic factor (produced by gastric parietal cells) and is then absorbed by enterocytes in the ileum

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10
Q

Where are vitamin B12 and folate absorbed?

A

Vitamin B12 = ileum

Folate = duodenum and jejunum

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11
Q

Where is intrinsic factor produced?

A

Parietal cells of the gastric mucosa

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12
Q

Where is vitamin B12 mainly found?

A

The liver

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13
Q

What is the function of vitamin B12 and folate?

A

They are required for the synthesis of DNA (converting homocysteine –> methionine), in their absence the cell fails to divide post-replication, leading to the production of one larger RBC

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14
Q

Why does vitamin B12/folate deficiency lead to macrocytic anaemia?

A

Impairs DNA synthesis (can’t convert homocysteine into methionine) so there is failure to divide into 2 new cells, so instead the cell remains as one larger cells

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15
Q

What conditions may cause a normocytic anaemia?

A

Sickle cell, anaemia of chronic disease (reduced production of RBCs), haemolysis, uncompensated increased plasma volume, vitamin B2/B6 deficiency

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16
Q

How can chronic disease lead to the development of anaemia?

A

Reduced life-span of RBCs due to infection/cancer/inflammation, but there is also reduced production due to bone marrow having a poor response to EPO or reduced EPO production due to inflammatory cytokines interring with this process (IL-1, TNFa)

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17
Q

Outline the mechanism of metabolism in red blood cells

A

Anaerobic: produce ATP via glycolysis and lactic acid fermentation of the produced pyruvate as well as using the pentose phosphate pathway

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18
Q

Outline the acquired causes of haemolytic anaemia

A

Autoimmune haemolytic anaemia (warm and cold), microangiopathic haemolytic anaemia (mechanical damage to RBCs) and infection (malaria

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19
Q

Outline the hereditary causes of haemolytic anaemia

A

Enzyme defects (G6PD deficiency, pyruvate kinase deficiency), haemolobinopathies (sickle cell, thalassaemia), membrane defects (hereditary spherocytosis and elliptocytosis)

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20
Q

Describe warm autoimmune haemolytic anaemia

A 
IgG mediated (cold is IgM) causes extravascular haemolysis and spherocytosis 
Cause = CLL, lymphoma, idiopathic 
Treatment = steroids and immunosuppression
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21
Q

Describe cold autoimmune haemolytic anaemia

A

IgM-mediated, causes extravascular haemolysis and spherocytosis
Cause = may follow infection EBV, mycoplasma
Treatment = keep warm

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22
Q

Describe G6PD deficiency

A

X-linked condition (affects boys mainly)
GP6D usually produces gluthionine to prolong RBC life-span
Presentation: asymptomatic until trigger (java beans, infection)
Blood film: bite and blister cells

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23
Q

Describe pyruvate kinase deficiency

A

Autosomal recessive

Reduced ATP production –> reduced RBC survival

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24
Q

Describe hereditary spherocytosis and elliptocytosis

A

Autosomal dominant
Extravascular haemolysis due to becoming trapped in the spleen
> Elliptocytosis can be protective against malaria
Treatment: folate

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25
Q

Describe microangiopathic haemolytic anaemia

A

Mechanical damage to RBCs causes intravascular haemolysis

Causes: HUS, ITP, DIC, prosthetic valve (pre)-eclampsia

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26
Q

How do signs of haemolytic anaemia differ from those of normal anaemia?

A

There is usually jaundice, organomegaly, gallstones (can be pigmented due to increased bilirubin from haemolysis), and leg ulcers in addition to the normal presentation

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27
Q

What is meant by ‘extravascular haemolysis’?

A

Breakdown is outside of the blood vessels e.g. spleen

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28
Q

What is meant by ‘intravascular haemolysis’?

A

Where RBC breakdown occurs within the blood vessels e.g. due to ABO mismatched transfusions, snake bites and infections

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29
Q

What common drugs may induce haemolytic anaemia?

A

Cephalosporins, levodopa, methyldopa, nitrofurantoin, NSAIDs

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30
Q

What are the signs of severe/complicated malaria?

A 
Impaired consciousness/seizures
AKI
Shock
Hypoglycaemia
Pulmonary oedema
Hb <80g/L
Spontaneous bleeding/DIC
pH <7.3
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31
Q

What’s the most common bacterium implicated in malaria?

A

Plasmodium falciparum, second is plasmodium viva

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32
Q

Explain sickle cell disease

A

Autosomal recessive; single amino acid substitution (GAG–>GTG) causes valine to present instead of glutamic acid at codon 6 of B-globin chain –> produces abnormal haemoglobin S that distorts RBCs into a crescent shape at low oxygen levels

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33
Q

What mode of inheritance does sickle cell disease have?

A

Autosomal recessive

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34
Q

What is alpha thalassaemia, generally?

A

Where one or more of the alpha genes on chromosome 16 are deleted/faulty

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35
Q

Which chromosome is implicated in alpha thalassaemia?

A

Chromosome 16

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36
Q

Which chromosome is implicated in beta thalassaemia?

A

Chromosome 11

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37
Q

What is alpha thalassaemia minima?

A

1/4 of the alpha genes on chromosome 16 are defective –> no clinical symptom

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38
Q

What is alpha thalassaemia minor?

A

2/4 of the alpha genes on chromosome 16 are defective –> normal production of RBCs with mild microcytic, hypochromic anaemia

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39
Q

What is alpha thalassamia major (Haemoglobin H disease)?

A

3/4 of the alpha genes on chromosome 16 are defective –> very little HbA can be produced –> high levels of unstable Hb Barts (4 gamma units) or Hb H (4 beta units) –> which have greater O2 affinity –> more difficult to transfer oxygen to the tissues.

Clear microcytic, hypochromic anaemia

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40
Q

What is hydrops fetalis?

A

Where 4/4 of the alpha genes on chromosome 16 are defective –> the only Hb present is Hb Barts (4 gamma units) which is incompatible with life

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41
Q

What is beta thalassaemia, generally?

A

Where there is a point mutation in the B-globin region on chromosome 11

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42
Q

How is sickle cell disease diagnosed at newborn screening?

A

Haemoglobin isoelectric focusing (IEF) shows elevated HbF at first, later in life there is higher HbS and no presence of HbA

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43
Q

How does beta thalassaemia trait differ from beta thalassamia major?

A

Trait = microcytic anaemia that is compensated (slightly increased levels of HbA2, 2x alpha and 2x delta globin chains) with normal HbA and HbF.

Major = severe microcytic anaemia with absent HbA and increase HbA2 and HbF

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44
Q

How is sickle cell disease managed?

A

Hydroxycarbamide - if they have frequent crises (to increase HbF)

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45
Q

What are the three different types of sickle cell crisis?

A

Vaso-occlusive - microvascular occlusion –> ischaemia
Aplastic - due to parvovirus B19 –> sudden reduction in RBC production by bone marrow
Sequestration - pooling of blood in spleen/liver

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46
Q

What is a vaso-occlusive sickle cell crisis?

A

Painful crisis due to microvascular occlusion. It’s triggered by cold, dehydration, infection or hypoxia.

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47
Q

What is a aplastic sickle cell crisis?

A

Due to parvovirus B19 –> sudden reduction in RBC production by the bone marrow. Usually self-limiting

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48
Q

What is a sequestration sickle cell crisis?

A

Pooling of blood in the spleen and/or liver, presenting with organomegaly, severe anaemia and shock. Urgent transfusion is required.

Doesn’t tend to occur in adults as the spleen becomes atrophic in sickle cell disease.

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49
Q

Why are those with sickle cell disease more vulnerable to infection?

A

Microvascular occlusion usually causes splenic infarction before the age of two, reducing the immune system of the individual and increasing their susceptibility to infection

50
Q

What are the causes of polycythaemia (increased numbers of RBCs)?

A

Relative
Absolute: primary = polycythaemia vera, secondary = hypoxia (high altitude, lung disease, cyanotic heart disease, heavy smoking) or inappropriate EPO production (renal or hepatocellular carcinoma)

51
Q

What is polycythaemia vera?

A

Malignant proliferation of haematopoietic stem cells in the bone marrow due to a mutation in JAK2 (95% cases) –> hyper viscosity and thrombosis

52
Q

What is the role of neutrophils?

A

First response to bacterial and fungal infection

53
Q

What increases and decreases the number of neutrophils?

A 
Increases = bacterial infection, inflammation, trauma, burns
Decreases = viral infection, cytotoxic/chemotherapy drugs, severe sepsis, neutrophil antibodies (SLE, haemolytic anaemia), hypersplenism
54
Q

What is the role of lymphocytes?

A

Cell-mediated immunity and antibody production

55
Q

What increases and decreases the numbers of lymphocytes?

A 
Increase = acute viral infection, chronic infection, leukaemia/lymphoma 
Decrease = steroids, HIV, chemo/cytotoxic therapy,
56
Q

What is the role of eosinophils?

A

Mediate allergic reactions and defend against parasites

57
Q

What increases and decreases the numbers of eosinophils?

A

Increase = allergies, parasitic infection (Helminths), skin disease (eczema, psoriasis)

58
Q

What is the role of monocytes?

A

Act as tissue macrophages (engulf pathogens to present them)

59
Q

What increases and decreases the numbers of monocytes?

A

Increase = aftermath of radio/chemotherapy, chronic infection, malignant disease

60
Q

What is the role of basophils?

A

Response to IgE-mediated hypersensitivity to release histamine

61
Q

What increases and decreases the numbers of basophils?

A

Increase = myeloproliferative disease, viral infection, IgE mediated hypersensitivity (asthma, hay fever, hives/urticaria), inflammatory disorders (UC, RA)

62
Q

What type of cells stem from the common myeloid progenitor?

A

Megakaryocytes, mast cells, myeloblasts (which then forms granulocytes)

63
Q

What type of cells stem from the common lymphoid progenitor?

A

Natural killer cells, T and B lymphocytes (and then antibodies)

64
Q

How do you handle a patient on a ward who has neutropenia?

A

Full barrier nursing in side room
Avoid IM injections (danger of infected haematoma)
Keep the patient as clean as possible

65
Q

What is meant by the two-hit model of leukaemia?

A

Loss of function of transcription factors needed for differentiation of cells
Gain of function mutations fo tyrosine kinase to enhance proliferation

66
Q

Name some examples of myeloproliferative disorders

A

CML, polycythaemia vera, essential thrombocytosis, primary/idiopathic myelofibrosis

67
Q

What is petechiae?

A

Red speckles on the skin due to superficial bleeding (can be related to thrombocytopenia)

68
Q

What are the common causes of thrombocytopenia?

A

Reduced production: leukaemia, liver failure, sepsis, vitamin B12/folate deficiency
Increased destruction: ITP, TTP, HUS, DIC, SLE, Zika and Dengue

69
Q

Give examples of 5 drugs that can inhibit platelet function

A

Valproic acid - prevents epilepsy
Methotrexate - immunosuppressant (IBD)
Carboplatin - alkylating chemotherapy agent
Interferon - treatment of cancer or Hep C
PPI - treatment of GORD

70
Q

Explain how balance is maintained between clot production and degradation.

A

t-PA is released into the blood very slowly by damaged endothelium of the blood vessels, such that when the bleeding has stopped (several days later) the clot is broken down

71
Q

Which substances are involved in the breakdown of clots?

A

Tissue plasminogen activator (t-PA) and urokinase work to convert plasminogen –> plasmin –> breaks down the fibrin mesh in clots

72
Q

What factor is deficient in haemophilia A?

A

Factor 8

73
Q

What factor is deficient in haemophilia B?

A

Factor 9

74
Q

What is the mode of inheritance of haemophilia?

A

X-linked recessive

75
Q

What clotting screen aspect would be increased in both haemophilia and vWF disease?

A

Increased APTT (intrinsic pathway affected)

76
Q

What are the two main inherited bleeding disorders?

A

Haemophilia and vW disease

77
Q

Which clotting factors does vitamin K deficiency affect?

A

10, 9, 7, 2 (1972)

78
Q

What are the potential causes of vitamin K deficiency?

A

Haemorrhagic disease of the newborn (no bacterial gut synthesis of vitamin K)
Biliary obstruction (malabsorption of vitamin K)
Liver disease (ineffective use of vitamin K)
Use of warfarin (vitamin K antagonist)

79
Q

What is haemorrhage disease of the newborn?

A

Where the newborn has no bacterial gut synthesis of vitamin K so requires vitamin K supplementation at birth

80
Q

How can kidney disease lead to impaired platelet function?

A

Reduced clearance of toxins by the kidney leads to increased levels of urea –> uraemia –> inhibits platelet function

81
Q

What is diffuse intravascular coagulation (DIC)?

A

Widespread intravascular deposition of fibrin –> using up all of the clotting factors and platelets –> bleeding due to depletion of coagulation proteins and platelets

Causes: infection, malignancy, liver disease, ABO mismatch post-transfusion, shock

82
Q

What are the causes of DIC?

A

Causes: infection, malignancy, liver disease, ABO mismatch post-transfusion, shock

83
Q

What’s the mechanism of action of LMWH, fondaparinux and DOACs?

A

Inactivates factor Xa

84
Q

What’s the mechanism of action of unfractionated heparin (UFH)?

A

Binds to antithrombin

85
Q

What’s the mechanism of action of warfarin?

A

Inhibits reductase enzyme responsible for regenerating vitamin K –> deficiency in 10, 9, 7 and 2 clotting factors

86
Q

What’s the mechanism of action of tranexamic acid?

A

Competitively inhibits the conversion of plasminogen to plasmin (so prevents clot breakdown)

87
Q

Why may desmopressin be prescribed to a patient with haemophilia A?

A

Works to stimulate the production of clotting factor 8

88
Q

What is meant by ‘Virchow’s triad’?

A

A triad associated with increased risk of developing VTE:

1) Endothelial damage (smoking/HTN, surgery, trauma)
2) Hyper-coagulability (Factor V Leiden, cancer, pregnancy, HRT, obesity, chemotherapy)
3) Stasis (immobility, polycythaemia)

89
Q

Are all UK blood products leukocyte deplete?

A

Yes - to reduce the incidence of any complications

90
Q

Outline the potential complications from blood transfusion

A

Acute haemolyrtic reaction (due to ABO incompatibility) - STOP transfusion, keep IV line open with saline
Anaphylaxis - STOP transfusion, maintain airway and give oxygen, contact anaesthetist
Bacterial contamination - STOP transfusion and start broad-spectrum antibiotics
TRALI (transfusion-related acute lung injury) - STOP transfusion, start 100% oxygen and remove donor from donor panel
Non-haemolytic febrile transfusion reaction - stop/slow transfusion and give paracetamol
Allergic reaction - slow/stop transfusion and give antihistamine
Fluid overload - stop transfusion

91
Q

How would an acute haemolytic reaction to blood transfusion present and how would you manage it?

A

(Due to ABO incompatibility)
Signs = agitation, rapid temperature spike, low BP, flushing, abdo/chest pain
Mx = stop transfusion, send off all cultures, keep IV line open with saline and treat DIC if present

92
Q

How would an anaphylaxis to blood transfusion present and how would you manage it?

A 
Signs = bronchospasm, cyanosis, low BP
Mx = stop transfusion, maintain airway
93
Q

How would an acute bacterial contamination blood transfusion present and how would you manage it?

A 
Signs = rapid temperature spike, low BP and rigors
Mx = stop transfusion and start broad spectrum antibiotics
94
Q

How would a non-haemolytic febrile transfusion reaction to blood transfusion present and how would you manage it?

A 
Signs = shivering and fever 30mins-1hr after starting transfusion
Mx = slow/stop transfusion, give paracetamol and monitor
95
Q

How would an allergic reaction to blood transfusion present and how would you manage it?

A 
Signs = urticaria and itch
Mx = slow/stop transfusion, give antihistamine and monitor
96
Q

How would a transfusion-related acute lung injury present and how would you manage it?

A 
Signs = dyspnoea, cough, CXR shows white out
Mx = stop transfusion, give 100% oxygen and remove donor from donor panel
97
Q

When is the adminstration of clotting factor concentrate contraindicated?

A

In the presence of DIC

98
Q

When might you administer packed red cells?

A

Anaemia (Hb 70-80) and blood loss

99
Q

When might you administer platelet concentrate?

A

If there is continuous bleeding or a platelet count <20

100
Q

When might you administer fresh frozen plasma?

A

Clotting defects e.g. DIC, warfarin overdose, liver disease, TTP

101
Q

When might you administer cryoprecipitate?

A

Haemophilia (when clotting concentrate isn’t available)

102
Q

When might you administer human albumin solution?

A

To replace protein in liver disease or nephrosis (usually as a treatment for ascites)

103
Q

When might you administer clotting factor concentrate?

A

Haemophilia

104
Q

Where is IgA found and what’s it’s function?

A

Found in mucus, saliva, tears and breast milk. Protects against pathogens

105
Q

Where is IgD found and what’s it’s function?

A

Part of the B cell receptor, it activates basophils and mast cells

106
Q

Where is IgE found and what’s it’s function?

A

Protects against parasitic worms and is responsible for allergic reactions

107
Q

Where is IgG found and what’s it’s function?

A

Secreted by plasma cells in the blood and is able to cross the placenta to the foetus

108
Q

Where is IgM found and what’s it’s function?

A

May be attached to the surface of a B cell or secreted directly into the blood. This antibody is responsible for the early stages of immunity

109
Q

What is meant by ‘paraproteinaemia’?

A

The presence of excessive amounts of paraprotein in the blood, usually due to an underlying immunoproliferative disorder e.g. multiple myeloma

110
Q

Describe acute lymphoblastic leukaemia (ALL)

A

Most common childhood cancer
Involved immature lymphoblasts
Hyperdiploidy is common (twice the normal amount of chromosomes)
Normocytic anaemia, low platelets and high WCC

Presence of philadelphia chromosome gives a worse disease prognosis

111
Q

Describe acute myeloid leukaemia (AML)

A

Involves myeloid precursor cells

Bloods: macrocytic anaemia, low platelets, high leukocytes, AUER RODS (ELONGATED STRUCTURES OF GRANULES)

112
Q

Describe chronic lymphocytic leukaemia (CLL)

A

Involves mature B cells
Presentation: 65-70 year olds
Bloods: normocytic anaemia, low platelets, high WCC, mild neutropenia

113
Q

Describe chronic myeloid leukaemia (CML)

A

Associated with philadelphia chromosome
Phases: chronic (3-5 years), accelerated (3-6 months), blast crisis (3 months then death)
Blood: normocytic anaemia, high platelets, high WCC, agranulocytosis
Treatment: imatinib (bcr-abl inhibitor)

114
Q

What are myelodysplastic syndromes?

A

Conditions that cause abnormal production of cells in the bone marrow

115
Q

Describe myeloma

A

Tumour of plasma cell proliferation
Presents with PARAPROTEINAEMIA, back pain, high calcium, recurrent bacterial infection, renal impairment (light chain deposition)
Blood: normocytic anaemia, ROULEAUX CELLS

116
Q

Who often presents with myeloma?

A

70+ Black Males

117
Q

Describe lymphoma

A

Malignant proliferation of lymphocytes (90% are B cells)

Lymph node pain when drinking alcohol, non-tender lymph node enlargement

118
Q

What’s the difference between leukaemia and lymphoma?

A

In lymphoma malignant cells begin in the lymph nodes, in leukaemia they are in the bone marrow.

119
Q

What is the Philadelphia Chromosome?

A

Recipricol translocation of chromosome 9:22 causing the fusion of bcr-abl –> uncontrolled tyrosine kinase activity –> uncontrolled cell proliferation

Mainly implicated in CML

120
Q

What symptom is characteristic of lymphoma

A

Lymph node pain induced by drinking alcohol

Year 3 General (2 decks)

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