Haemophilia Flashcards
What is haemophilia?
A rare CLOTTING disorder.
Inheritance of haemophilia?
X-linked recessive
What are the 2 main types of haemophilia?
A & B
What is Haemophilia A characterised by?
Factor VIII deficiency
Which type of haemophilia is most common?
A
What does haemophilia B arise due to?
Factor XI deficiency
Pathophysiology of haemophilia?
1) Factor VIII or IX deficiency interferes with the intrinsic pathway of the coagulation cascade
2) Decreased activation of Factor X to Xa
3) Reduces generation of thrombin (thrombin is critical for converting fibrinogen to fibrin)
4) Clot is fragile and susceptible to premature lysis
5) Manifests as prolonged bleeding
Where does bleeding typically occur in haemophilia?
Bleeding into deep tissues e.g. muscles & joints
What is the severity of symptoms in haemophilia generally proportionate to?
The degree of factor deficiency
What is haemophilia B also known as?
Christmas disease
What clotting factor is deficient in haemophilia A?
Factor VIII
What clotting factor is deficient in haemophilia B?
IX
What is haemophilia C?
Rosenthal syndrome.
It is a deficiency of clotting factor XI that is inherited in an autosomal recessive pattern.
How does inheritance of haemophilia impact who is affected?
X-linked recessive nature means men are almost exclusively affected.
Features of haemophilia?
1) Haemarthrosis (bleeding into a joint)
2) Easy bruising
3) Prolonged bleeding after dental procedure
4) Muscular haematomas e.g. quads, calves
5) Epistaxis
6) GI symptoms e.g. melaena or haematemesis
How does haemoarthrosis typically present?
Painful, erythematous, stiff and swollen joint
Classically the knees, ankles and elbows.
A significant portion of cases of haemophilia present in the neonatal period (40%).
What features may be seen in neonates?
1) Prolonged bleeding after circumcision
2) Intracranial bleeding (up to 5% of severe cases)
- Can be due to trauma from delivery ie forceps
3) Prolonged bleeding after heel prick testing
When should haemophilia be suspected?
In younger patients with prolonged hemorrhage, ecchymosis (bruising) or haemarthrosis.
Bloods tests in haemophilia?
1) FBC –> look specifically for thrombocytopenia to rule out platelet dysfunction.
2) Clotting studies
3) LFTs –> to rule out liver synthesis dysfunction
4) Factor VIII and IX assays
5) Von Willebrand factor antigen testing.
What clotting study result represents a delay in the intrinsic coagulation pathway? (i.e. one of the hallmarks of haemophilia)?
Prolonged activated partial thromboplastin time (aPTT)
Why is prothrombin time (PT) useful in haemophilia diagnosis?
A normal PT can rule out extrinsic and common coagulation pathway pathologies that could present similarly e.g. liver disease.
What is the most common differential diagnosis to consider in haemohpilia?
von Willebrand disease
Mx of haemophilia?
Replacing missing coagulation factors:
A –> VIII
B –> IX
What medications is it important to avoid in haemophilia?
Aspirin & NSAIDs
Complications of haemophilia?
1) Compartment syndrome related to muscular bleeding
2) Arthropathy from haemarthrosis
3) Severe haemorrhage (Intracranial, GI)
