Week 10: Bleeding and Clotting disorders Flashcards
Which are the intrinsic pathway clotting factors
8, 9, 11, 12
Which are the extrinsic pathway clotting factors
7
Which are the Vit K dependent clotting factors
2, 7, 9, 10
Does APTT assess the intrinsic or extrinsic pathway
APTT = intrinsic
Does PT assess the intrinsic or extrinsic pathway
PT = extrinsic
What is the purpose of a blood mixing study?
What products are mixed?
To determine the cause of a long APTT
APTT is mixed with normal plasma
When APTT is mixed with normal plasma (mixing study), APTT time CORRECTS.
What condition does this show?
Clotting factor deficiency
When APTT is mixed with normal plasma (mixing study), APTT time DOES NOT CORRECT.
What condition does this show?
Clotting factor inhibitor
eg lupus anticoagulant
Which factor is deficient in haemophilia A
Factor 8
Which factor is deficient in haemophilia B
Factor 9
Inheritance of haemophilia
X-linked
Inheritance of Von Willebrand’s disease
Autosomal dominant
Function of Von Willebrand factor
- Binds to and stabilises factor 8 (prevents it from being proteolysed)
- Binds platelets to sub-endothelium
Desmopressin (DDAVP) is used in treatment of Von Willebrand’s disease. What is its mechanism of action?
Desmopressin causes release of VwF stored in the endothelium
Precipitating events for DIC
- Sepsis
- Trauma, major bleed
- Cancer
- Incompatible blood transfusion
- Liver disease
- Obstetric catastrophe eg placental abruption, pre-eclampsia
In DIC, how are the following blood tests changed
- APTT
- PT
- platelets
- fibrin
- d-dimer
APTT: increased PT: increased Platelets: decreased Fibrin: decreased D-dimer: increased
Complications of DIC
Organ failure
-due to tissue ischaemia from intravascular fibrin deposition
Risk factors for developing VTE
- Age
- Immobilisation
- Surgery
- Air travel
- Cancer
- Pregnancy
- OCP, HRT
- Anti-phospholipid antibodies
- Thrombophilia
Which are the naturally occurring anticoagulants
- Protein C
- Protein S
- Antithrombin
Describe the pathophysiology of Factor V Leiden disease
Point mutation in Factor 5 gene at APC cleavage site.
Anticoagulant cannot link efficiently onto 5a to inactivate it -> slow inactivation
Which anticoagulant inactivates Factor 5
Protein C
Which anticoagulant drugs have a rapid onset
- Heparin
- Apixaban
- Dagibatran
Which anticoagulant drugs have a slow onset
Warfarin
What INR level tends to be associated with intracerebral haemorrhage
INR 2-3.5
