Von willebrands disease all are true except – a) Factor VIII C deficiencyb) B.T. Prolongedc) Normal Ristocetin testd) Defective aggregation
Von Willebrand disease is characterized by the deficiency of vWF, while the synthesis of factor VIIIc is normal.
VWF has two major functions -


Helps in platelet adhesion
Stabilizes factor VIIIc


So, deficiency of vWF results in manifestation of both -

1) Platelet adhesion defect

Bleeding from small venules and capillaries of skin and mucous membrane e.g. epistaxis. a Menorrhagia and GI bleeding
Prolonged bleeding time

2)   Coagulation defect (due to factor VIII dysfunction)

Bleeding into weight bearing joints
Large post traumatic ecchymoses or hematoma
Prolonged bleeding after any form of surgical procedure or a laceration.
Prolonged PTT
VWF can be assayed by ristocetin agglutination test which measures the ability of ristocetin to promote the interaction between VWF and platelet membrane glycoprotein Ib-IX.
a
bc
ac
b