Differentials
Mild haemophilia A
SIGNS / SYMPTOMS
Bleeding symptoms may be similar, although patients with VWD tend to have more mucosal bleeding symptoms.
By family history, VWD is inherited in an autosomal pattern and haemophilia in an X-linked pattern.
However, because of the high mutation rate in haemophilia A and because of variable expressivity in VWD, a positive family history may be absent in both.
INVESTIGATIONS
Patients with haemophilia A have decreased factor VIII but normal VWF antigen and activity. For VWD all 3 are decreased. Special binding studies or DNA analysis is required to distinguish type 2N VWD from haemophilia A.
Inherited platelet function disorder
SIGNS / SYMPTOMS
Both platelet function disorders and VWD have predominant mucosal bleeding symptoms.
Rare severe platelet function disorders such as Glanzmann's thrombasthenia and Bernard-Soulier syndrome are autosomal recessive in inheritance, but most inherited platelet function disorders are autosomal dominant.
INVESTIGATIONS
Platelet aggregometry is abnormal in inherited platelet disorders and normal in VWD.
In non-type 2B VWD there may be decreased sensitivity to ristocetin induced platelet agglutination, but this is less sensitive for the diagnosis of VWD than the ristocetin cofactor assay.
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