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Advanced Haematology > Week 6 > Flashcards

Week 6 Flashcards

1
Q

List 3 contents of a platelet?

A

lysosomes, granules and membrane,

microtubules

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2
Q

Granules are key in primary hemostasis; list some things that they contain (6)

A
  • ADP
  • Thromboxane
  • Platelet factor 4
  • Adhesive and aggregation glycoproteins
  • Coagulation factors
  • Fibrinolytic inhibitors
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3
Q

What stage in hemostasis does platelet aggregation initiate?

A

Secondary hemostasis through the coagulation cascade

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4
Q

Coagulation system needs to be regulated

or it would continually produce what?

A

thrombi.

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5
Q

Clotting factors have antagonists what are they?

A

Anti-coag agents that can cleave them.

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6
Q

Define thrombosis

A

inappropriate formation of platelet or fibrin clots that

obstruct blood vessels.

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7
Q

List two resulting risks of thrombosis

A

ISCHEMIA i.e loss of blood flow,

NECROSIS i.e. tissue death.

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8
Q

List some contributors to thrombosis

A
  • Blood flow e.g. stasis
  • Coagulation system
  • Platelet function
  • Leucocyte activation molecules
  • Blood vessel walls
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9
Q

EMBOLI = fragments of thrombi - how can this cause ischemia?

A

move to right chamber of heart

  • lodge in arterial pulmonary vasculature
  • cause ischaemia & death of lung tissue
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10
Q

What are 3 types of arterial thrombosis?

A

Myocardial infarction
Cerebrovascular accidents
Transient ischaemic attacks (TIA)

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11
Q

Atherosclerosis is fatty plaque with what 3 things?

A
  • Activated platelets
  • Monocytes
  • Macrophages
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12
Q

Atherosclerosis suppresses the release of ___________ molecules like Nitric oxide and Exposes __________ substances like Tissue factors

A

anti-thrombotic, prothrombotic

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13
Q

In atherosclerosis unstable plaques rupture, releasing what?

A

thrombotic mediators - platelets + vWF, minimal fibrin

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14
Q

List 3 risk factors for atherosclerosis.

A
  • Total cholesterol
  • LDL-cholesterol
  • HDL-cholesterol
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15
Q

Factor V Leiden, Prothrombin G20210A are common genetic mutations relating to what?

A

CONGENITAL thrombosis

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16
Q

APC acts as an anticoagulant by proteolytically inactivating which 2 factors? and which protein enhances this anticoag activity

A

FVa & FVIIa

Protein S

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17
Q

WARFARIN impacts which proteins?

A

Prot C, S & Z

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18
Q

Antithrombin is a serine protease inhibitor (serpin) which binds an neutralises all serine proteases except which factor?

A

FVIIa

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19
Q

What is prothrombin G20210A

A

Mutation at base 20210 in the

prothrombin (FII) gene.

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20
Q

Mildly increased prothrombin levels leads to increased risk of what?

A

increased risk of thrombosis

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21
Q

Factor V Leiden is most common inherited cause of increased risk of venous thrombosis. T-F

A

T

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22
Q

Normally APC breaks down which factor?

A

FVa

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23
Q

Factor V Leiden is a variant of which factor?

A

V

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24
Q

Factor V Leiden is a mutation because of a _____ ______ substitution. Factor V Leiden is also a mutation that makes FV resistant to ______ cleavage

A

amino acid, APC

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25
Q

T-F; FV Leiden mutation also known as APC resistance

A

T

26
Q

List some Acute causes of DIC

Hint: Deficiencies of multiple haemostasis components.

A

Obstetric emergencies, Septicaemia, viraemia

Burns, Acute inflammation, Crush injuries, Aortic aneurysm, Cardiac disorders

27
Q

List some Chronic causes of DIC

A

Liver disease, Renal disease, Chronic inflammation, Prosthetic devices, Vascular tumors

28
Q

DIC is characterised by loss of normal ______ control

in response to sustained systematic injury

A

haemostatic

29
Q

In thrombocytopenia what happens to the production, destruction, and distribution of platelets?

A

Decreased production, increased destruction and abnormal distribution

30
Q

What are the 2 categories of abnormalities in platelet PRODUCTION?

A

Megakaryocyte hypoplasia, Ineffective thromobopoiesis

31
Q

Is Acute ITP (idiopathic thrombocytopenia purpura) primarily seen in children or adults?

A

children

32
Q

Acute ITP Usually manifest 1 to 3 weeks after an __________

A

infection

33
Q

In Chronic ITP _________ coated platelets are destroyed in RE system

A

Antibody

Autoantibodies in 50% of cases

34
Q

ITP patient blood film morphology
• RBC and leucocytes _______
• Platelets _____________
• MPV

A

RBC and WBC - normal
Platelets - reduced in number, may be large
MPV may be increase

35
Q

In ITP Coagulation studies what would the results be for tests that rely on platelet function

A
  • Abnormal

* Bleeding time, clot retraction time

36
Q

Immune mediated thrombocytopaenia can be secondary to what conditions?

A
  • Chronic lymphocytic leukaemia
  • System lupus erythematosus
  • Parasitic infection e.g. Malaria
37
Q

The mechanism of _________ is to bind to antithrombin, enhance inhibition of FIIa, FXa. Used for prophylaxis against thrombosis

A

Heparin

38
Q

What is the mechanism in Heparin induced thrombocytopenia (HIT)?

A

develop IgG Antibody to heparin – Platelet Factor 4 complex

39
Q

Heparin induced thrombocytopenia leads to what 3 things?

A

Platelet activation
Decreased platelet count
Formation of microvascular thrombi

40
Q

HELLP syndrome stands for …..

A

Haemolysis, Elevated Liver enzymes, Low Platelet count

41
Q

Thrombotic thrombocytopaenic purpura caused by a RARE inherited mutation of which gene?

A

ADAMTS13

42
Q

What cleaves vWF into smaller fragments?

A

ADAMTS13

43
Q

Cleaved fragments of vWF bind to what?

A

exposed collagen

44
Q

Platelets some receptors bind to vWF, others

to what?

A

fibrinogen

45
Q

In TTP the ADAMTS13 enzyme is deficient or blocked

by an __________, cleaving of large multimeric vWF chains is inhibited

A

autoantibody

46
Q

Large chains of multimeric vWF bind to areas of
endothelial damage, and initiate recruitment of
large numbers of _______ into large aggregates

A

platelets

47
Q

Large numbers of sites with large platelet

aggregations cause what 3 potential things?

A
  • Thrombocytopaenia
  • Microangiopathic haemolytic anaemia
  • Organ ischaemia
48
Q

Large numbers of sites with large platelet

aggregations cause what 3 potential things?

A

• Thrombocytopaenia
• Microangiopathic haemolytic anaemia
• Organ ischaemia
TAI

49
Q

Is TTP intravascular or extravascular

haemolysis?

A

Intravascular

50
Q

What would you expect to find on a blood film of a patient with TTP?

A

Schistocytes, low platelets, polychromasia

51
Q

What would you expect the PT, APTT and fibrinogen test results be for a patient with TTP

A

Normal PT, APTT, fibrinogen - note these results differentiate TTP from DIC.

52
Q

What form of therapy would restore the presence of ADAMTS13 enzyme, reduces platelet aggregation in small vessels.

A

Plasma infusion

53
Q

What would dilute the autoantibodies to ADAMST13?

A

Plasma exchange

54
Q

What is the name of the CD20 binding

monoclonal antibody that binds to the B-cells that are producing the autoantibody, mediating their destruction

A

Rituximab

55
Q

Haemolytic uraemic syndrome (HUS) resembles what other disorder?

A

TTP

HUS is seen mainly in children 6 mths to 4 years

56
Q

90% of cases of haemolytic uraemic syndrome relate to presence of bacteria in GI tract. Which bacteria?

A
  • Shigella dysenteriae → Shiga toxin

* Eschericia coli

57
Q

In HUS and TTP which features predominantly renal and which features predominantly neurological?

A

HUS - Renal

TTP - Neurological

58
Q

Give 2 examples of a qualitative disorder of adhesion receptors. (tip) both are - Rare, autosomal recessive disorders

A
  1. Bernard-Soulier Syndrome (BSS) or Giant platelet syndrome

2. Glanzmann Thromboasthenia

59
Q

What would be the treatment for bernand-soulier syndrome, and Glanzmann Thromboasthenia?

A

Platelet transfusions → Develop allo-antibodies

60
Q

What would the results of aggregation studies for Bernard-Soulier Syndrome (BSS) be for
ADP, epinephrine, collagen & AA, Ristocetin

A

Normal to ADP, epinephrine, collagen & AA
NO response to Ristocetin (instab of P :VWF binding)
↓ response to thrombin

61
Q

What would the lab findings be for Glanzmann Thromboasthenia? FBC, Platelet count, Bleeding time, Platelet aggregation studies

A 
FBC: Normal
Platelet count : Normal
Bleeding time: prolonged 
Platelet aggregation: Risto – normal
Others NO response

Advanced Haematology (13 decks)

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