Laboratory
Tests for
von Willebrand
Disease

Bleeding time

How long does it take to stop bleeding? This finding is related to both the number and function of platelets and the amount of von Willebrand factor.

Factor VIII clotting activity

This measurement, which is low or nonexistent in people with haemophilia A, is usually normal or only slightly lowered in people with von Willebrand disease. The measurement takes into account not just the level of Factor VIII, but also its ability to function.

vWF antigen

This measures the amount of von Willebrand factor. Those with mild disease usually have 25-35% of the normal amount. Those with severe disease have less than 5%. A person’s blood type may affects these levels.

Ristocetin cofactor activity

A measurement of how well the von Willebrand factor is working.

vWF multimers

Evaluates the structure of the von Willebrand factor molecule. Helps in correctly classifying the type of von Willebrand disease.

Platelet function tests

Measure how well platelets work. Helps identify the type of von Willebrand disease or other disorder.