Haemophilia

• Haemophilia is a largely inherited bleeding disorder of variable severity

  The deficiency can be quantitative or qualitative
• Haemophilia A is caused by a factor VIII deficiency
• Haemophilia B (Christmas disease) is caused by a factor IX deficiency
• Haemophilia C is caused by a factor XI deficiency
• Pathophysiology:

  • Factor VIII and factor IX genes are located on the X chromosome
  • Passed down in a recessive fashion
  • Males with a single mutation will have the disease
  • Females will be carriers
  • Both factor VIII and IX are involved in the intrinsic pathway - slowing the rate of secondary plug formation and risking blood loss through the fragile primary plug
• Mild haemophilia patients often do not release they have the disease and only present after a bleed following major trauma or surgery, or precipitated by drugs such as NSAIDs or aspirin
• Severe haemophilia will typically present early with spontaneous or prolonged bleeding:

  • Severe epistaxis
  • Bleeding gums
  • Haematuria
  • Intramuscular bleeds - commonly knees, ankles or elbows
  • Excessive bruising
  • Rare - intracranial haemorrhage, haematemesis, melaena or haemoptysis
• Investigations:

  • FBC - low Hb and haematocrit. Normal platelet count.
  • PT/INR normal
  • Bleeding time can be normal - enough activation of the extrinsic pathway
  • Normal vWF
  • Prolonged APTT
  • Coagulation factor assay - reduced factor VIII or IX
• Management - prophylaxis:

  • Severe haemophilia may require factor infusions
  • Factor infusions prior to surgery
  • Tranexamic acid
  • Regular monitoring of factor levels and calculation of haemophilia joint health score
  • Avoid contact sports
  • Medical ID bracelet
  • Hep A and B vaccinations - increased risk of infection with regular transfusions
  • Avoid IM injections
• Management - acute bleeds:

  • Mild haemophilia A - desmopressin - stimulates vWF which promotes factor VIII
  • Factor infusions
  • Fresh frozen plasma
  • Cryoprecipitate - concentrated clotting factors
• ·       Before 1985, factor concentrate was created from multiple blood donations

  ·       Many haemophilia patients infected with bloodborne viruses- HIV, hepatitis B and C
• A mixing study is another useful investigation of haemophilia. By mixing a haemophilia patient’s blood plasma in a 1:1 ratio with normal plasma, a prolonged APTT should normalise. This is because the normal plasma contains functional clotting factor, so the deficiency can be bypassed.
• Acquired haemophilia is a rare but severe bleeding disorder - development of autoantibodies against coagulation factors, most commonly factor VIII