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Department of Pediatrics : Academic Divisions : Emergency Medicine : Resident Manual : Hematology & Oncology : Hemophilia A & B

Hemophilia A: Factor VIII deficiency and Hemophilia B: Factor IX deficiency (Christmas Disease)

Both are X-linked recessive disorder

Normal Factor activity is 50-150%

Severity of Hemophilia A and B (based on factor activity level)

  • Mild: 5-25% - bleeding with surgery or trauma
  • Moderate: 1-5% - bleeding with mild injury
  • Severe: < 1% (most common) - spontaneous bleeding

Clinical manifestations (hemophilia A & B are indistinguishable)

  • Hemarthrosis (most common)
  • Soft tissue hematomas (e.g., muscle)
  • Other sites of bleeding:
    • Urinary tract
    • CNS, neck (may be life-threatening)
  • Prolonged bleeding after surgery or dental extractions

Laboratory diagnosis

  • Both will cause prolonged aPTT with normal pT
  • DO NOT OBTAIN BLEEDING TIME (NOT DONE ANYMORE)
  • Low Factor VIII (hemophilia A) and Factor IX (hemophilia B)
  • Factor VIII deficiency can be diagnosed at birth as newborns including premies have normal levels
  • Factor IX deficiency may be difficult to diagnose at birth as it is low up to 6 months of age (exception severe cases with positive family history)

Treatment guidelines
Recombinant Factor products

  • Factor VIII (Helixate-FS), Factor IX (Benefix)
  • Dosing: One unit/kg of Factor VIII increases plasma factor activity by 2%. Example: To obtain 50% factor activity in a 25kg child with hemophilia A, you need to give 625 Units of Helixate (FVIII dose (U) = body weight (kg) X desired FVIII increase (%) X 0.5 U/kg)
  • Whereas, one unit/kg of Factor IX increases plasma factor activity by 1%. Example: To obtain 50% factor activity in a 25kg child with hemophilia B, you need to give 1250 Units of Benefix (FIX dose (U) = body weight (kg) X desired FIX increase (%) X 1U/kg)
  • Mild bleeding
    • Hemarthrosis, oropharyngeal or dental, epistaxis, hematuria
    • Target: 30-40% factor activity; 1-2 days
  • Major bleen
    • CNS trauma, hemorrhage, lumbar puncture
    • Surgery
    • Retroperitoneal hemorrhage
    • GI bleeding
    • Target: 80-100% factor activity; 7-14 days

Adjunctive therapy
Amicar (epsilon aminocaproic acid)
Anti-fibrinolytic agent useful in mucocutaneous bleeds
Dose: 100mg/kg/dose q6hours PO for 4-5 days
Contraindicated in patients with hematuria (it can cause clots in urogenital system)

DDAVP

  • Useful only in mild Hemophilia A patients (it releases FVIII from endothelial cells)
  • Dose: 0.3 µg/kg q 12 hr IV for only maximum of 3 days Or Stimate nasal spray (150 mcg) (for children >5 years) one spray if < 50Kg or two sprays >50kg for only maximum of 3 days
  • Dose and formula is different from treatment of enuresis
  • Side effects: Flushing, hyponatremia -seizures, tachyplaxis
  • Need to have DDAVP challenge test to assess the patient's response (done soon after diagnosis)
  • Contraindicated in children < 2 years (causes dilutional hyponatremia)


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