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Haemophilia
Haemophilia

Haemophilia

Haemophilia is a bleeding disorder that is an X- linked recessive disorder. This means that males are the only individuals that can be affected.

There are 2 types of haemophilia to consider:

  1. Haemophilia A - deficiency of factor VIII.
  2. Haemophilia B - deficiency of factor IX. Also known as Christmas disease.

🏃 Physiology

Let’s review our coagulation cascade once again (primary haemostasis can be revisited in the CCC on patient on anti-platelet therapy).

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We have 3 pathways to consider…

  1. Intrinsic pathway - activated primarily by collagen which in turn activates factor XII → factor XIIa which then activates factor XI → factor XIa which then activates factor IX → IXa. This finally activates factor VIII to activate factor X in the common pathway.

    2. Remember the intrinsic has 12, 11, 9 and 8.

  2. Extrinsic pathway - this is activated by subendothelial tissue which releases tissue factor (TF). TF then activates factor VII which then activates factor X in the common pathway.
  3. Common pathway - kicks off with factor Xa (activated by either intrinsic or extrinsic pathway). This then activates prothrombin (factor II) → thrombin (IIa) with the help of factor Va.

    4. Thrombin is used to convert factor I (fibrinogen) to factor Ia (fibrin). This then activates factor XIII → factor XIIIa which crosslinks fibrin which becomes incorporated into the platelet plug to stabilise the clot.

😷 Presentation

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  • ⭐️ Recurrent or severe bleeding - neonates present typically with prolonged bleeding following heel prick or circumcision.
    • ⭐️ Haemarthroses - bleeding into joints
    • ⭐️ Musculoskeletal bleeding - patients have swelling and pain in the extremities with decreased range of motion, erythema and increased warmth. It may also lead to compartment syndrome if there is a large bleed into a compartment.
    • Mucocutaneous bleeding - epistaxis, gum bleeding.
    • Neonates present with intracranial haemorrhage, haematomas and cord bleeding.
  • Bruising easily and haematoma formation

🔍 Investigations

  1. 🥇 Prolonged aPTT - aPTT measures factor XII, XI, IX or VIII. This is why we use it as opposed to thrombin times or prothrombin times (measures factor VII)
    • Bleeding time, thrombin time and prothrombin times will be normal.
  2. 🏆 Plasma factor VIII and IX assay
  3. 🏆 Genetic testing

🧰 Management

Specialists should manage the patient.

🥇 IV infusions of clotting factors VIII (for haemophilia A) or XI (for haemophilia B). However, 10-15% of patients develop antibodies to the clotting factor, rendering this vital treatment ineffective. Cryoprecipitate contains mostly factor VIII (as well as fibrinogen, von Willebrand Factor, and factor XIII).

In acute episodes of bleeding or prophylactically during surgery, we can give:

  • IV infusions of clotting factors
  • Desmopressin - stimulates release of vWF.
  • Antifibrinolytics such as tranexamic acid.