Lecture 8: Coagulation Disorders (Parts I & II)

Question 1

Compare Glanzmann’s Thrombasthenia (GT) and Bernard-Soulier Syndrome (BSS):

Answer 1

GT:
Defect in αIIbβ3 (no fibrinogen binding)
Normal platelet count
Aggregometry: No response to agonists

BSS:
Defect in GPIb-IX-V (no vWF binding)
Thrombocytopenia + giant platelets
Aggregometry: No response to ristocetin

Question 2

What is the first-line treatment for severe bleeding in GT?

Answer 2

Platelet transfusions or NovoSeven® (rFVIIa).

Question 3

What causes TTP?

Answer 3

ADAMTS13 deficiency → uncleaved vWF multimers → platelet microthrombi.

Treatment: Plasma exchange (replenishes ADAMTS13).

Question 4

Lab findings in DIC?

Answer 4

↓Platelets, ↑PT/APTT, ↑D-dimer, ↓fibrinogen (consumption coagulopathy).

Question 5

Which inherited thrombophilias increase thrombosis risk?

Answer 5

Factor V Leiden (APC resistance).

Protein C/S deficiency (↓anticoagulation).

Prothrombin G20210A (↑prothrombin levels).

Question 6

Why does Factor V Leiden cause thrombosis?

Answer 6

Mutation makes FV resistant to cleavage by Protein C → unchecked thrombin generation.

Question 7

What is purpura fulminans?

Answer 7

Life-threatening skin necrosis due to severe Protein C/S deficiency.

Question 8

How is ITP diagnosed?

Answer 8

↓Platelets (<100×10⁹/L), normal PT/APTT, exclusion of other causes.

Treatment: Steroids, IVIG.

Question 9

What test confirms HIT (Heparin-Induced Thrombocytopenia)?

Answer 9

Anti-PF4/heparin antibodies + platelet activation assays (e.g., serotonin release).

Question 10

Key feature of antiphospholipid syndrome (APS)?

Answer 10

Lupus anticoagulant (prolongs APTT but causes thrombosis).