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vWF Deficiency

von Willebrand Factor (vWF) Deficiency: Authors: Tristan Jones, Nimaya De Silva Reviewers: Sean Spence, Yan Yu, Paige Shelemey, Tony Gu, Raafi Ali, Man-Chiu Poon*, Lynn Savoie* * MD at time of publication Pathogenesis and clinical findings Inherited Acquired Autosomal dominant inheritance Recessive inheritance Type III: Complete quantitative vWF deficiency Presence of antibodies to vWF (a blood clotting protein involved with platelet adhesion), often in setting of autoimmune disease Antibodies bind and inactivate existing vWF Clonal lympho-proliferative disease (uncontrolled production of lymphocytes, a type of immune cell) Adsorption of vWF multimers on to tumor cells ↑ Plasma clearance of vWF ↓ vWF to stabilize/carry plasma Factor VIII (blood clotting protein) ↓ Plasma Factor VIII Impaired intrinsic pathway of coagulation cascade (see Calgary Guide slide on coagulation cascade) Type I: Partial quantitative vWF deficiency Type II: Impaired vWF function (qualitative deficiency) ↓ Binding to vWF-specific antibody on immunoassay ↓ vWF antigen assay (diagnostic test for quantitative vWF deficiency) ↑ Bleeding/closure time (bleeding time measures the length of time required to form a platelet plug) Spontaneous hematomas (large collection of blood outside the blood vessels) Menorrhagia (heavy menstrual bleeds) vWF Deficiency ↓ vWF quantity and/or function ↓ vWF available to bind to damaged blood vessel collagen to anchor platelets Impaired platelet plug formation Bleeding from mucosal surfaces Easy bruising Gum bleeding ↑ Time for blood clot to form Risk of severe hemorrhage ↑ Partial Thromboplastin Time (PTT) (measures the integrity of the intrinsic pathway) Epistaxis (nose bleed) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-published December 5, 2023 on www.thecalgaryguide.com