Diagnosing von Willebrand Disease
Von Willebrand disease is the most common inherited bleeding disorder. Most people with this condition have a genetic mutation that prevents the body from making enough von Willebrand factor—a protein “glue” that helps blood cells called platelets stick to the walls of blood vessels so that the blood begins to clot, which stops bleeding. In others, a mutation prevents the protein from working properly.
People with this condition may have bruising after little or no apparent trauma, frequent nosebleeds, bleeding after flossing teeth, and heavy menstrual periods. People with von Willebrand disease also tend to bleed more heavily and for a longer time than others after surgical and dental procedures. These symptoms can be bothersome but are not usually life-threatening.
Most people with the condition have the mildest form, type 1, in which the body does not make enough von Willebrand factor. In type 2, the protein doesn’t work properly and the body cannot make enough of it, leading to frequent bleeding. Type 2 von Willebrand disease is often divided into subtypes, based on the kind of abnormal protein the body makes. In type 3, the body makes very little or no von Willebrand factor, causing severe bleeding episodes. This type is similar to mild hemophilia.
A child who inherits one defective von Willebrand gene from a parent who is a carrier but has no symptoms has an increased risk for developing type 1 or 2. The most severe form, type 3, occurs when a child inherits a defective gene from both parents.
Specialists at Hassenfeld Children’s Hospital at NYU Langone are experienced in making an accurate diagnosis, even in children with the mildest form of von Willebrand disease, whose symptoms may be missed by others.
Medical History and Physical Exam
At Hassenfeld Children’s Hospital, diagnosing von Willebrand disease begins with a complete medical history. The doctor may ask about the frequency or severity of your child’s symptoms and any other medical conditions, such as liver disease, or medications your child takes regularly, such as nonsteroidal anti-inflammatory drugs, both of which may increase the risk of bruising. The doctor may also ask about symptoms in other family members, including siblings and parents, to determine if there is a family history of von Willebrand disease.
The doctor may perform a physical exam to look for signs of bruising or recent bleeding in the muscles and joints.
Blood test results can determine if your child has von Willebrand disease and, if so, which type. A small amount of your child’s blood is drawn in the doctor’s office and is sent to a laboratory for evaluation. Tests may include any of the following:
- prothrombin time and partial thromboplastin time tests, in which blood is put into a machine that measures the time it takes the blood to clot
- von Willebrand factor antigen test, which measures the amount of this protein in your child’s blood
- factor VIII test, which measures levels of another protein involved in blood clotting and how well it’s working
- von Willebrand factor ristocetin cofactor test, which shows how well the von Willebrand factor is working in your child’s body
- von Willebrand factor multimer test, which evaluates the structure of the protein and can determine the type of von Willebrand disease your child has
It may take up to one week for your doctor to receive the blood test results. If any of the results suggest a bleeding disorder, the doctor may recommend repeating certain tests and that family members also be tested to see if they have the condition.