• PT = 11.2 seconds (ref = 11.2)
• aPTT = 42 seconds (ref = 22-34)
• CBC
• Factor VIII (enzymatic)
• 55% (ref 50-150%)
• von Willebrand factor
• vWF Antigen: decreased
• Ristocetin cofactor activity: down

• Platelet aggregation to Ristocetin; reduced
• This factor VIII-vWF sounds like a complicated protein. Tell me about it.
• Factor VIII-vWF is a complex made of two functionally distinct proteins.
• VIII is the X-linked enzymatic pro-coagulant that activates factor X.
• The majority of VIII is made in the liver.
• vWF is the autosomally coded component made by endothelial cells and megakaryocytes. 
• When released into the blood it combines with the enzymatic VIII.
• VIII-vWF molecules assemble into larger multimeric aggregates.
• vWF facilitates platelet adhesion to subendothelial collagen, and
• platelet to platelet adhesion

So, does Mrs. KL have von Willebrand disease?                                            Back