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TAS > Haematology > Flashcards

Haematology Flashcards

1
Q

Haematopoeisis

A

Process through which all types of mature blood cells are produced

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2
Q

What do Erythroid / megakaryocytic lineage cells give rise to?

A

Red cells and platelets

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3
Q

What do granulocyte/ macrophage lineage give rise to?

A

Granulocytes and monocytes

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4
Q

What do lymphoid lineage give rise to?

A

T cells, B cells and NK cells

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5
Q

Primitive haematopoeisis

A

Started in yolk sac
Give rise to red blood cells

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6
Q

When is primitive haematopoeissi replaced by definitive haematopoiesis at?

A

5-6 weeks gestation

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7
Q

What is definitive haematopoiesis?

A

Produces all blood cell types

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8
Q

Where are definitive heamtopoietic stem cells created?

A

Develop in the aorta-gonad mesonephros region of the dorsal aorta

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9
Q

When do HSC’s migrate to AGM to fetal liver and spleen?

A

6-7 weeks gestation
Liver is then the primary site of haematopoiesis

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10
Q

What is main site of heamtopoiesis at 3rd trimester and at birth?

A

Bone marrow
Originally occurs in all areas of bone marrow - restricted to axial skeleton and proximal ends of long bones later

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11
Q

What does metal Hb consist of? When does it start getting produced in gestation?

A

2 alpha chains, 2 gamma chains
Produced from 3-4 weeks of fatal life

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12
Q

What does the binding and releasing of oxygen cause?

A

Causes small configuration of globin chains in Hb molecule
Oxygen is unloaded, Hb molecule opens up allowing 2,3-diphosphoglcyerate (2-3 DPG) to enter reducing oxygen affinity and ensuring Hb molecule does not take up oxygen from tissues

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13
Q

What is average life span of RBC?

A

120 days in older children and adults
90 days in neonates

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14
Q

Iron absorption

A

Iron in diet is absorbed by enterocytes in duodenum either in Fe2+ form or as haem
Ferroportin, iron transporter protein, transports iron across basolatereal membrane of enterocyte into the blood stream
Iron binds to transferrin and transported to tissues

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15
Q

Transferrin

A

Transferrin can bind to 2 molecules of iron and deliver this to cells that express transferrin receptors

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16
Q

Ferritin

A

Storage of iron
Shows total body iron levels (in absence of inflammation)

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17
Q

Why are Hb values higher in utero? What are the values?

A

Higher oxygen affinity of HbF and fall during first few months of life
Neonate - <130
1-12 months <100
1- 12 years <110

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18
Q

Causes of Reduced MCV - microcytosis

A

Iron deficiency
Thalassaemia major or thalassaemia trait
Anaemia of chronic disease

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19
Q

Causes of increased MCV - macrocytosis

A

Folate deficiency
Vit B12 deficiency
Diamond-Blackfan anemia
Liver Disease
Hypothroidism

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20
Q

Diamon-Blackfan Aneamia

A

Genetic disorder
Presents with anaemia at birth or during infancy
50% physical abnormalaties - craniofacial abnormalities, thumb and growth restrictions
Autosomal dominant
Mutations in ribosomal protein genes - RPS19
Bone marrow biopsy
Treatment - steroids and regular blood transfusions

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21
Q

Transient erythroblastopenia

A

Parvovirus-induced red cell aplasia
TEC - presents 2 year olds
Transient red cell aplasia triggered by unknown infective agent
Recovery occurs spontaneously within 4-8 weeks
Normocytic with neutropenia

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22
Q

Blood tests for Haemolytic Anaemia

A

Reduced Hb
Raised reticulocytes - immature red blood cells
Raised unconjugated bilirubin
Raised LDH

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23
Q

Intravascular haemolysis

A

Occur in circulation
Depletion of haptoglobin
Increase LDH
Large numbers of fragmented RBCs (schisocytes)

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24
Q

Extravascular haemolysis

A

Takes place in spleen or liver - can occur in lung
Spleen or liver macrophage Fc receptors bind immunoglobulin attached to RBC

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25
Q

Inherited haemolytic disorders

A

Red cell membrane defects - hereditary spherocytosis, hereditary ellipocytosis
Red cell enzyme defects - G6PD deficiency and pyruvate kinase deficiency
Haemoglobinopathies - sickle cell disorders, thalassaemias

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26
Q

Acquired Haemolytic disorders

A

Autoimmune - idiopathic, SLE, JIA
Microangiopathic - HUS, TTP, haemangiomas
Infection - Malaria, septicaemia
Other - burns, lead poisoning

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27
Q

What conditions cause Positive DAT’s

A

Haemolytic disease of newborn
Autoimmune haemolytic anaemia
Drug-induced anaemia
Haemolytic transfusion reactions

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28
Q

Red cell enzyme defects

A

Glucose-6-phosphate dehydrogenase deficiency
Pyruvate kinase deficiency

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29
Q

What does G6PD do?

A

Protects cell from oxidative damage
Catalyses first step of pentose phosphate pathway

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30
Q

How is G6PD deficiency inherited?

A

X-linked disorder

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31
Q

What causes an acute haemolytic crisis in G6PD deficiency

A

Infection
Medications - co-trimoxazole, dapsone, nitrofurantoin, chloramphenicol, chloroquine, aspirin

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32
Q

Blood results in acute haemolytic crisis

A

Reduced Hb
Raised reticulocytes
Hyperbilibuinaemia
Increased LDH

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33
Q

Blood film in G6PD deficiency

A

fragmented red cells ‘bite’ cells and polychromasia
Heinz bodies (denatured hB)

Not in crises - blood film normal

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34
Q

Pyruvate kinase deficiency

A

Results in sufficient ATP production
Causes rigid cells and haemolysis

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35
Q

How is pyruvate kinase deficiency inherited?

A

Autosomal recessive

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36
Q

Pyruvate kinase deficiency blood film

A

Prickle red cells

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37
Q

Autoimmune haemolytic anaemia - what it is and types

A

Produce antibody against their own red cells
Types - warm and cold (depends if antibody binds most strongly at 37 degrees or 4 degrees)

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38
Q

Warm AIHA

A

usually IgG antibodies

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39
Q

Cold AIHA

A

usually IgM antibodies

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40
Q

Blood results in AIHA

A

unconjugates hyperbilirubinaemia
Raised LDH
Increased retidulocytes
Reduced heptoglobin levels
Postive DAT

41
Q

Treatment in AIHA

A

Immunosuppressive treatment - steroids, azathioprine, cyclosporin

42
Q

Lead poisoning - bloods and blood film

A

Microcytic anaemia
Blood film - basophilic strippling (basophilic granules seen in RBC)

43
Q

Thalassaemias

A

Genetic defect that results in reduced rate of synthesis of alpha-globin or beta-globin chains

44
Q

alpha thalassaemia

A

Gene deletion of a-globin
Normally inherit 4 (each copy of chromosome 16 has 2 copies)
Deletion of one or two = trait, asymptomatic
Loss of all 4 = a-thalassaemia major = death in utero or hydrops fetalis = death in few hours of birth

45
Q

haemoglobin H disease

A

Deletion of 3 alpha globin genes = HbH disease
Microcytic hypo chromic
Splenomegaly
Excess of B-globin chain forms an abnormal Hb called HbH - consists of only B-globin chains
Detected - high-performance liquid chromatogaphy HPLC

46
Q

Beta thalassaemia

A

mutations in B-globin gene (2 copies chromosome 11)
excess of a-globin as result - precipitate in erythrocytes = anaemia 2nd to ineffective erythropoiesis and haemolysis
Blood film - target cells, nucleated red blood cells and basophilic stippling

47
Q

What age dose beta thalassaemia present?

A

3-6 months
Hb production switched from HbF to HbA
HbF = a-globin and gama globo
HbA = a-globin and beta-globing
6 month roughly 95% HbA

48
Q

Treatment for B-thalassaemia major

A

Regular blood transfusions
Careful iron overload - iron chelation therapy started 10-15 RBC transfusions given or serum ferritin increases above 1000 - desferrioxamine

49
Q

What causes Sickle Cell disease

A

Point mutation in b-globin gene= single amino acid change (valine for glutamine)
HbS is relatively insoluble and polymereizes when exposed to low oxygen tension
Creates sickle cells - dehydrated, rigid and less deformed = obstruct blood flow

50
Q

Types of sickle cell disease

A

Sickle cell anaemia - homozygous for B-globin mutations HbSS
HbSC disease - single b-globin mutation in combination wit hHbC mutation HbSC
S B-thalassaemia - B-thalassaemia mutation in combination with B-globin

51
Q

Types of sickle cell crisis

A

Veno-occlusive crisis (painful)
Sickle chest crisis
Splenic/ hepatic sequestration
Aplastic crisis - 2nd to parvovirus B19
Cerebral infarction

52
Q

Management of sickle cell disease

A
  • Avoid factors that may precipitate a crisis - cold, dehydration, over-strenuous exercise
  • Twice daily penicillin proph. and vaccination
  • Folic acid
53
Q

What dose Bone marrow failure cause

A

Pancytopenia

54
Q

Fanconi’s anaemia

A

Physical abnormalities - short stature, microcephaly, skin hyperpigmentation
Affected gene FANC genes BRCA 2

55
Q

Triad of Shwachman-Diamond syndrome

A

-Bone marrow failure
-Pancreatic insufficiency
-Skeletal abnormalities

56
Q

What is DIC

A

intravascular deposition of fibrinogen and consumption of coagulation factors and platelets

57
Q

What triggers DIC

A

Infection
Malignancy
Blood transfusion
Liver failure
Widespread tissue damage

58
Q

Coagulation screen - what does PT measure

A

II, V, VII, X

Extrinsic + common

59
Q

What clotting factors does APTT test for

A

II, V, VIII, IX, X, XI, XII

Intrinsic and common

60
Q

What clotting factors does thrombin time or fibrinogen test for

A

Fibrinogen

61
Q

Steps of heamostatis

A
  1. Vasconstriction
  2. Temporary platelet plugging
  3. Coagulation cascade
  4. Fibrinolysis
  5. Regeneration
62
Q

How do you test for 1st haemostatis (temporary platelet plugging(

A

Bleeding Tim e
PLT count
PLT aggregation

ANTI-PLATLETS

63
Q

What test do you use ?for testing coagulation

A

PT
aPTT
TT

64
Q

What is haemophilia A a factor defieicny of?

A

Factor 8

65
Q

What prolongs pt

A

Vit K defiency
warfarin
liver disease
factor VIII, III, x defiency
APS
heparin
DIC

66
Q

What prolongs aPTT

A

heparin
Haemophillia
Liver disase
aPS
warfarin
DIC

67
Q

What prolongs TT

A

Hypofibrinogen
Thombin inhibitor
Heparin
DIC
liver disease
warfarin

68
Q

Where do DOACs act?

A

Antirhombin and X

69
Q

MoA of heparin

A

Increased antithrombin

70
Q

How does haemophilia present

A

Presents with joint and soft tissue bleeding

71
Q

What are test results in haemophilia And B

A

Long aPTT, normal PT

72
Q

Treatment for haemophilia

A

Recombinant sources of clotting factors

73
Q

Complication of factor treatment

A

Development of inhibit antibodies that block efficacy of the factor

Most commonly ass. with factor 8

74
Q

What else can be used as an alternative to factor concentrate in mild haemophilia A

A

Desmopressin

Stimulates release of factor VIII and von Willebrand factor

75
Q

What is Von Willebrand factor

A

Large glcyoprotein present in endothelial cells and platelets

76
Q

What are the two main functions of VWF

A
  • Promote platelet adhesion to damaged endothelium
  • To bind and stables factor VIII, protecting It from proteolytic degradation
77
Q

Presentation fVWF disease

A

Mucosal bleeding
Menorrhagia
Easy brushing

78
Q

How do you diagnose VWF disease

A
  • prolonged APTT
  • Factor VIII: C will be reduced
  • VWF ristocetin cofactor assay
79
Q

How do antifibrinolytics work? (Tranexamic acid)

A

Prevent plasminogen to plasmin

Plasmin breaks down strands in fibrongen

80
Q

Which clotting factors are low at birth

A

Vitamin K dependent clotting factors

81
Q

What is immune thrombocytopenia purpura

A

Diagnosis of exclusion

82
Q

Treatment of ITP

A

Self-limiting

If fails to respond within 6 months (chronic iTP) - short course of steroids
With bone marrow sample prior to treatment
IV immunoglobulins can be used

83
Q

How does rituximab work

A

Anti-CD20 monoclonal antibody

B cells involved in pathogenesis of ITP

84
Q

Why is chicken pox an important cause of stroke in childhood

A

Reduction in anticoagulant Protein S - increases hisk of thrombosis

85
Q

What does Protein C do?

A

Inhibits factors V and VIII

85
Q

What does protein S do?

A

Enhances action sof protein C

86
Q

What is the most common inherited thrombophillia

A

Factor V leiden Mutation

Prevents protein C bind to and inhibiting factor V

86
Q

What are inherited risk factors of thrombosis

A

Defiencies of -
Antithrombin
Protein C
Protein S

87
Q

Aquired risk factors of thrombosis?

A

Presence of central venous line
Malignancy
DIC
SLE
Trauma
Polycythaemia

88
Q

ABO blood group system - group a

A

Antigens - A
Antibodies - Anti-B
Compatible groups - A, O

89
Q

ABO blood group systems - group B

A

Antigens - B
Antibodies - Anti-A
Compatible groups - B, O

90
Q

ABO blood groups - AB group

A

Anitgens - AB
Antibodies - none
Compatible group s- A, b, ab, O

91
Q

ABO groups - O group s

A

Antigen - none
Antibodies s- Anti - A, anti -B
Compatible O

92
Q

How to present RhD haemolytic disease of newborn?

A

Mum’s have blood group and antibody screen at booking
If were RhD negative - 28 weeks - another antibody screening to see if sensitisation
If lack anti-d antibodies in 2nd trimester - given anti-D prop 28- 34 weeks

If anti-D antibody detected - antibody levels need to be measured to predict risk of developing HDN

93
Q

How to calculate volume of red cell transfusions

A

Volume to be transfused = weight x Hb increment x 4

94
Q
A
95
Q
A
96
Q
A

TAS (18 decks)

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