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Department of Pediatrics : Academic Divisions : Emergency Medicine : Resident Manual : Hematology & Oncology : vonWillebrand's Disease

  • Most common inherited bleeding disorder worldwide.
  • von Willebrand factor is synthesized in endothelium and megakaryocytes and forms a large multimer to carry factor VIII and anchors platelets to subendothelium as bridge between platelets.
  • Inheritance - autosomal dominant
  • Clinical features - mucocutaneous bleeding; epistaxis, menorrhagia etc.

Classification

  • Type I: Partial quantitative deficiency of vWF (70% of cases, mild-moderate disease)
  • Type II: Qualitative deficiency of vWF (25% of casese, mild to moderate disease)
  • Type III: Total or near total deficiency of vWF (5% of cases, severe disease)

Diagnosis

  • Prolonged aPTT in 50% of cases (due to low factor VIII). Normal aPTT does not rule out vWD
  • Normal PT
  • Prolonged bleeding time; DO NOT PERFORM. This is replaced by PFA-100 which is not available at MUSC (assess platelet function)
  • Send vWF antigen level and activity, Factor VIII, Ristocetin cofactor assay, vWF multimeric analysis

Treatment

  • DDAVP: Useful in mild cases (Type I), contraindicated in Type IIB, not useful in Type III. See hemophilia section for dosing details
  • vWF replacement therapy: Humate-P (recombinant product): The dosage of Humate-P® required (IU VWF:RCo) = body wt. (kg) x desired % increase in VWF activity ÷ 1.5. As a rule, 40-80 IU VWF:RCo per kg body weight are given every 8-12 hours. The dose should be adjusted according to the type of VWD and the extent and location of the bleed.
  • Adjunctive therapy with Amicar (see hemophilia section)


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