WEEK 4: Disorders of Haemostasis

Question 1

what is haemostasis?

Answer 1

Haemostasis is the mechanism that leads to cessation of bleeding from a blood vessel

Question 2

what does a healthy endothelium produce? What do they do?

Answer 2

ecto-ADPase (CD39)and produces prostacyclin (PGI2) and nitric oxide (NO).
All these block platelet adhesion to and activation by healthy endothelium.

Question 3

what is primary haemostasis?

Answer 3

Primary haemostasis is the initial response of the body to vascular injury and involves the formation of the platelet plug

Question 4

what is quantitative platelet disorder?

Answer 4

thrombocytopenia (not enough) or thrombocytosis (too many)

Question 5

what is qualitative platelet disorder? How is it acquired if not inherited?

Answer 5

platelet functional defect can be inherited or acquired.
Acquired - drugs, alcohol, uremia and myeloproliferative disorders

Question 6

what is a normal platelet count?

Answer 6

Normal platelet count 150-350 x109/L

Question 7

how is a platelet disorder diagnosed?

Answer 7

Full blood count, then
blood film - do platelets look normal?
Clinical notes?
Platelet count.

Question 8

how is thrombocytopenia treated?

Answer 8

plasma exchange
administration of anti-thrombotic agents

Question 9

what does a defect in the glycoprotein on the surface of the 1b-IX-V. Bernard Soulier

Answer 9

platelet can’t bond to von willebrand factor.
Platelet plug cannot form well

Question 10

what does a platelet defect in Glanzmann thrombasthenia / IIb/IIIa cause?

Answer 10

doesn’t bind to fibrinogen

Question 11

does primary haemostasis involve the coagulation pathways?

Answer 11

no

Question 12

what is secondary haemostasis?

Answer 12

it is associated with the propagation of the clotting process via the intrinsic and extrinsic coagulation cascades, and fibrinolysis

Question 13

what do activated protein C and S do in the intrinsic pathway?

Answer 13

Activated protein C and S inactivate factor Va and FVIIIa. This confines thrombin generation to site of injury in healthy endothelium

Question 14

what happens when there’s a deficiency of protein C or S?

Answer 14

Deficiencies of protein C and S or defects that preventcleavage and inactivation of FV (FV Leiden) allow forthe spread of thrombi into the vasculature and areassociated with venous thrombisis

Question 15

what is hyperfibrinolysis?

Answer 15

Hyperfibrinolysis – disposes to bleeding and thrombosis. Plasmin inhibitor and Plasminogen inhibitor 1 prevent this

Question 16

what is hypofibrinolysis?

Answer 16

Hypofibrinolysis – deficiencies of t-PA or u-PA, plasminogen, contact factors. Associated with thromboembolic disease

Question 17

what is the central enzyme in fibrinolysis?

Answer 17

plasminogen

Question 18

what disorders can occur with a defect in factor 1/fibrinogen?

Answer 18

Afibrinogenaemia
Hypofibrinogenaemia
Dysfibrinogenaemia

Question 19

what bleeding disorders can occur with a defect in factor 1/fibrinogen?

Answer 19

Spontaneous bleeding, Spontaneous abortions/severe post-op bleeding

Question 20

what disorders can occur with a defect in factor 2?

Answer 20

Hypoprothrominaemia
Dysprothrombinaemia

Question 21

what bleeding disorders can occur with a defect in factor 2?

Answer 21

Mild to severe bleeding
Mucosal membrane bleeds

Question 22

how are disorders with a defect in factor 1 treated?

Answer 22

fresh frozen plasma
Cryoprecipitate to increase levels of fibrinogen.

Question 23

how are disorders with a defect in factor 2 treated?

Answer 23

Prothrombin complex concentrate

Question 24

what does a deficiency in factor 8 result in?

Answer 24

Haemophilia A

Question 25

how does a patient with haemophillia A present?

Answer 25

bleeds after trauma or surgery - severe cases means there could spontaneous bleeding.

Question 26

how is haemophilia A treated?

Answer 26

Recombinant Prophylaxis