A Case of Von Willebrand’s Disease

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A 16-year-old girl is sent to your office because she had a nose bleed during class and this was not the first time. The girl comes to your office saying that “I get these nosebleeds once in a while but they’re no big deal because they stop after about 10 minutes. But, I think I bleed a lot more during my period than my girlfriends do.” She also tells you that “my mother has some kind of bleeding problem, but she never speaks about it.” After some discussion, she informs you that that her brother was in the Betty Ford Clinic for cocaine addiction. You ask her if she is using and she says, “I’ve tried it a few times but I’m no crackhead like my silly brother.” What is the most likely diagnosis? Differentials • Coagulation disorders (secondary hemostasis), disorders with increased vascular fragility Relevant Physical Examination Findings • Physical examination is unremarkable. • No history of vomiting blood (hematemesis), passage of bloody stools (hematochezia), or black, tarry stools (melena) • No signs of ecchymoses (small hemorrhagic spots) Relevant Lab Findings • Blood chemistry:
  • platelets 250,000/L (normal);
  • prothrombin time (PT) 13 seconds(normal);
  • partial thromboplastin time (PTT) 65 seconds (high);
  • bleeding time 10 minutes (high)
  • Ristocetin assay no aggregation of platelets
Diagnosis: Von Willebrand Disease • Von Willebrand Disease (vWD). vWD is a type of primary hemostasis disorder and is the most common inherited bleeding disorder (autosomal dominant). vWD is due to low levels of vWF. Endothelial cells secrete vWF, which combines with factor VIII secreted by hepatocytes to form a factor VIII–vWF complex (this increases the half-life of factor VIII). This complex promotes blood clotting as well as platelet–subendothelial connective tissue interactions necessary for blood clotting. Platelets attach to the subendothelial connective tissue when the Gp1b glycoprotein receptor located on the cell membrane of the platelet binds to the factor VIII–vWF complex. Since vWF forms a complex with factor VIII, vWD patients have a qualitative (not quantitative) deficiency of factor VIII that leads to a prolonged PTT. Clinical findings of vWD include excessive bleeding from superficial cuts, bleeding from mucous membranes (e.g., gums, nasal mucosa), prolonged bleeding after dental work, menorrhagia, internal gastrointestinal bleeding, and easy bruising. Primary hemostasis disorders with a platelet count below 150,000/L (quantitative) include bone marrow failure, Wiskott-Aldrich syndrome, idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, multiple transfusions, and splenic sequestering. Primary hemostasis disorders with a normal platelet count (qualita tive) include vWD, Bernard-Soulier disease, Glanzmann thrombasthenia, aspirin overdose, and uremia. A prolonged bleeding time is diagnostic of a primary hemostasis disorder. • Coagulation Disorders (Secondary Hemostasis). Coagulation disorders are clotting factor deficiencies involved in the coagulation cascade. Coagulation disorders include hemophilia A, hemophilia B (Christmas disease), and vitamin K deficiency. A prolonged PTT is diagnostic of a coagulation disorder. Clinical findings of coagulation disorders include severe bleeding from large blood vessels with hemarthrosis, large hematomas after trauma, and prolonged wound healing. • Vascular Fragility. Diseases with increased vascular fragility include scurvy, Henoch Schönlein purpura, rickettsial and meningococcal infections, Ehlers-Danlos syndrome, and Cushing syndrome. Clinical findings of disorders with increased vascular fragility include symptoms similar to primary hemostasis disorders but with a normal bleeding time.
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