37 Heritable bleeding disorders Flashcards Preview

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Flashcards in 37 Heritable bleeding disorders Deck (33)
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1
Q

What is the platelet receptor for fibrinogen?

What does it do?

A

Glycoprotein 2β3A.

Platelet activation.

2
Q

What is the platelet receptor for vWF?

What does it do?

A

Glycoprotein 1B9.

Platelet adhesion.

3
Q

How does aspirin act?

A

Inhibits COX enzymes, inhibiting the formation of thromboxane. Platelets don’t activate.

4
Q

How does clopidogrel act?

A

Inhibits ADP receptors on platelets, preventing platelet activation.

5
Q

How do GIIβ/IIIA antagonists act?

A

Inhibit fibrinogen binding to platelets.

6
Q

Which factors are involved in the intrinsic coagulation pathway? (4)

A

XII.
XI.
IX.
VII.

7
Q

What initiates the intrinsic coagulation pathway?

A

Foreign surface.

8
Q

Which factors are involved in the extrinsic clotting pathway? (2)

A

VII.

TF.

9
Q

Which factors are involved in the common coagulation pathway? (4)

A

X.
V.
II. Thrombin.
Fibrinogen. Fibrin.

10
Q

What does the APTT measure?

A

Intrinsic and common pathway function.

11
Q

What does the prothrombin time measure?

A

Extrinsic pathway function.

12
Q

What is the extrinsic pathway activated by?

A

Tissue factor exposure.

13
Q

Which anticoagulant factors circulate in the blood? (4)

A

Protein C.
Protein S.
Anti-thrombin III.
Fibrinolytic system.

14
Q

Explain the fibrinolytic system.

A

TPA breaks down plasminogen to plasmin. Plasmin breaks down fibrin.
α2-AP mops up plasmin, protecting clotting pathway.

15
Q

What are the four types of platelet and vessel wall defects?

A

Reduced platelet number.
Abnormal platelet function (aspirin).
Abnormal vessel wall (Ehlers-Danlos).
Abnormal platelet-wall interaction (vWD).

16
Q

Describe the type of bleeding typically seen in platelet/vascular defects. (4)

A

Petechiae.
Skin and mucous membranes.
Spontaneous.
Immediate and non-recurrent.

17
Q

Describe the type of bleeding seen in coagulation defects? (4)

A

Deep haematoma.
Haemarthrosis.
Retroperitoneal.
Prolonged and often recurrent.

18
Q

What are the three types of von Willebrand disease?

A
  1. Decreased amount.
  2. Normal amount of low molecular weight polymer.
  3. Absent molecule.
19
Q

Which coagulation factor acts as a carrier protein for von Willebrand factor?

A

VIII.

20
Q

What are the features of von Willebrand disease?

Inheritance?

A

Variable reduction in FVIII levels.
Mucotaneous, post operative and post-partum bleeding.
Autosomal dominant.

21
Q

How is vWD treated? (5)

A
Antifibrinolytics: tranexamic acid.
DDAVP.
vWF concentrates.
Hepatitis vaccination.
COCP for menorrhagia.
22
Q

How does DDAVP work? (vWD Rx).

A

Increases release of vWF from stores.

Temporary effect that decreased on repeat dosing.

23
Q

Which hereditary coagulation factor deficiency is common in the Ashkenazi Jew population?

A

FXI.

24
Q

Which coagulation factor deficiency does not constitute a bleeding disorder?

A

FXII.

25
Q

Which coagulation factor deficiencies lead to a prolonged APTT?

A

XII.
XI.
IX.
VIII (vWD and haemophilia).

26
Q

Which coagulation factor deficiency leads to a prolonged PT?

A

VII.

27
Q

Which coagulation factor deficiencies lead to a prolonged APTT and PT? (5)

A
X.
V.
II.
I.
XIII.
28
Q

What are deficiencies seen in Haemophilia?

A

A: VIII.
B: IX.

29
Q

How is haemophilia inherited?

A

X linked recessive.
Expressed in males, carried in females.
Doesn’t get worse through generations.

30
Q

What are the degrees of severity in haemophilia?

A

Mild: 6-50%.
Moderate: 1-5%.
Severe: less than 1%

31
Q

How is haemophilia treated? (5)

A
Missing protein replacement. 
DDAVP.
Recombinant factor concentrates.
Antifibrinolytics.
Vaccination against Hep A + B.
32
Q

What is the major complication of haemophilia treatment?

Treated?

A

Inhibitor development.
Occurs in A > B.
Results in poor response to treatment.
Rx: eradication of inhibitor through very high dosage.

33
Q

Name 6 causes of bleeding with normal coagulation screens.

A
Thrombocytopenia.
Platelet abnormalities.
vWD.
Factor XIII deficiency.
Vascular disorder.
Disorder of fibrinolysis.

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