BOF: Clotting (Haemophilia)

A 12 year old boy presents with recurrent epistaxis. Blood results show Hb 12 g/dL, Plts 170 x 10⁹/L, APTT ratio 1.5, INR 1.1, FVIIIc 40%, PFA 100 – prolonged closing times with both ADP and epinephrine. Platelet aggregation studies show an absence in response to ristocetin. Which ONE of the following diagnoses is MOST likely?

a) Accidental aspirin use

b) Bernard Soulier disease

c) Liver disease

d) Mild haemophilia A

Answer:

Type 1 vWD

Explanation:

With evidence of platelet dysfunction in the clinical history (muco-cutaneous bleeding) and laboratory assays, as well as an intrinsic pathway defect conferring a prolonged APTT due to low FVIIIc, the picture is most suggestive of VWD. Von Willebrand factor's many functions are conferred by multiple binding sites and contribute to effective platelet aggregation as well as retention of factor VIII in the circulation hence maintaining physiological levels.

Reference:

Laffan M, Brown SA, Collins PW et al. The diagnosis of von Willebrand disease: a guideline from the UK Haemophilia Centre Doctors' Organization. Haemophilia 2004 May;10(3):199-217.