von Willebrand Disease Screen

Description: 
von Willebrand Factor (vWF) is a large multimeric glycoprotein (multimer). It is synthesised by endothelial cells and megakaryocytes. The multimer has adhesive properties and two main functions:

• A carrier for the Factor VIII coagulation protein which is non-covalently bound to the multimer. The binding stabilises Factor VIII when it circulates in the plasma.

• A mediator of platelet binding to collagen via the platelet glycoprotein Ib receptor.

von Willebrand’s disease is the most common congenital bleeding disorder with a frequency of 1 per 100,000. It is characterised by skin and mucosal bleeding and the bleeding time is usually prolonged. The disorder is caused either by reduced levels of the multimer as a whole (quantitative defect), or defects in its structure due to reduced levels of parts of the multimer (qualitative defect). There are several sub-classes of the disease and differential diagnosis is important as clinical management differs depending upon sub-class. Increased levels of vWF are found in vascular disease and when endothelial damage is present; after exercise and during pregnancy. Increases indicate stimulation of endothelial cells. Endothelial cells can be induced to produce vWF by administration of drugs such as adrenaline and DDAVP (1-deamino 8-d-arginine vasopressin).

Laboratory diagnosis includes measurement of Factor VIIIc activity, vWF antigen and vWF activity. Reduced levels of vWF will also give prolonged results in the bleeding time test.
Reference range: 

For healthy adults:

vWF activity:

The Normal Range is 50 – 150 u /

vWF antigen :

Normal Range is 50-150 u/dl

Factor VIII is : 50 - 150 u/dl

Sample type and Volume required: 
Three tri-sodium citrate samples to be sent directly to the laboratory.
Turnaround time: 
Done in batches which are run as and when there is a batch Results may be obtained much sooner after prior arrangement with laboratory.
Storage and transport: 
Samples should be kept at room temperature and must be received and processed in the laboratory within an hour of venipuncture. If sent frozen the samples must be kept frozen during transportation on dry ice.
Cost: 
Please contact Business Development for pricing enquiries
Contacts:
Routine Coagulation - Blood Sciences at King's College Hospital
020 3299 2434
King's College Hospital
Bessemer Wing
Denmark Hill
London SE5 9RS
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 07/08/2015