37 Heritable bleeding disorders Flashcards

1
Q

What is the platelet receptor for fibrinogen?

What does it do?

A

Glycoprotein 2β3A.

Platelet activation.

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2
Q

What is the platelet receptor for vWF?

What does it do?

A

Glycoprotein 1B9.

Platelet adhesion.

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3
Q

How does aspirin act?

A

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

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4
Q

How does clopidogrel act?

A

Inhibits ADP receptors on platelets, preventing platelet activation.

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5
Q

How do GIIβ/IIIA antagonists act?

A

Inhibit fibrinogen binding to platelets.

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6
Q

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

A

XII.
XI.
IX.
VII.

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7
Q

What initiates the intrinsic coagulation pathway?

A

Foreign surface.

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8
Q

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

A

VII.

TF.

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9
Q

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

A

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

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10
Q

What does the APTT measure?

A

Intrinsic and common pathway function.

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11
Q

What does the prothrombin time measure?

A

Extrinsic pathway function.

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12
Q

What is the extrinsic pathway activated by?

A

Tissue factor exposure.

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13
Q

Which anticoagulant factors circulate in the blood? (4)

A

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

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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.

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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).

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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?

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?

24
Q

Which coagulation factor deficiency does not constitute a bleeding disorder?

25
Which coagulation factor deficiencies lead to a prolonged APTT?
XII. XI. IX. VIII (vWD and haemophilia).
26
Which coagulation factor deficiency leads to a prolonged PT?
VII.
27
Which coagulation factor deficiencies lead to a prolonged APTT and PT? (5)
``` X. V. II. I. XIII. ```
28
What are deficiencies seen in Haemophilia?
A: VIII. B: IX.
29
How is haemophilia inherited?
X linked recessive. Expressed in males, carried in females. Doesn't get worse through generations.
30
What are the degrees of severity in haemophilia?
Mild: 6-50%. Moderate: 1-5%. Severe: less than 1%
31
How is haemophilia treated? (5)
``` Missing protein replacement. DDAVP. Recombinant factor concentrates. Antifibrinolytics. Vaccination against Hep A + B. ```
32
What is the major complication of haemophilia treatment? | Treated?
Inhibitor development. Occurs in A > B. Results in poor response to treatment. Rx: eradication of inhibitor through very high dosage.
33
Name 6 causes of bleeding with normal coagulation screens.
``` Thrombocytopenia. Platelet abnormalities. vWD. Factor XIII deficiency. Vascular disorder. Disorder of fibrinolysis. ```