von Willebrand Profile

Factor VIII Activity, von Willebrand Antigen, von Willebrand Activity

7 days

See individual tests

50-160%

Ideally, the patient should not be on anticoagulation therapy. Avoid heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing. Do not draw from an arm with a heparin lock or heparinized catheter. Indicate and provide details if patient is on anticoagulant.

Accredited NRL Laboratory

Once a week

Comprehensive panel for diagnosing von Willebrand deficiency

Plasma

2 aliquots, each containing minimum 1ml of plasma

Sodium citrate (Light blue top), filled to the line

Plasma should be platelet free as possible. Platelet count should be less than 10 x 109/L. Double centrifugation: Perform centrifugation for 15 mins at 2000-2500 g. Carefully remove 2/3 of plasma using a transfer pipette without disturbing the interface layer between plasma and cells. Transfer plasma to a plastic aliquot tube and repeat the centrifugation step. Using a second pipette, separate plasma again into another plastic aliquot tube, staying clear of the platelet layer at the bottom of the tube. Freeze immediately (no longer than 2 hours after collection) and maintain frozen until tested.