Because many people with von Willebrand disease have very mild signs, the condition can be difficult to diagnose. If you have any indication of a bleeding disorder, your doctor may refer you to a blood disorders specialist (hematologist). This doctor will perform specific blood tests to diagnose or rule out von Willebrand disease. These tests may be repeated to confirm that the diagnosis of von Willebrand disease is correct and to determine the disease type.
Classifications of the disease
There are three major types of von Willebrand disease:
- Type 1. In this most common form of von Willebrand disease, levels of von Willebrand factor are low. In some people, levels of factor VIII also are low. Signs are usually mild.
- Type 2. In this type, which has several subtypes, the von Willebrand factor that is present doesn't function properly. Symptoms tend to be more significant.
- Type 3. In this rare type, von Willebrand factor is altogether absent and levels of factor VIII are low. Signs may be severe, such as bleeding into the joints and muscles.
- Acquired von Willebrand disease. This type isn't inherited from your parents. It develops later in life, possibly due to an autoimmune disease, a thyroid condition or certain medications.
In general, tests to diagnose von Willebrand disease include:
- Medical history and physical exam. Your doctor will likely begin by asking detailed questions about your medical history since childhood, including specifics about past bleeding episodes. He or she will ask whether your parents or siblings have had bleeding problems. Your doctor will also check for bruises or other signs of recent bleeding.
- Blood tests. Your doctor likely will recommend a combination of blood tests to diagnose von Willebrand disease. The results of these tests can fluctuate in the same person over time due to factors such as stress, excessive exercise, blood transfusions, recent surgery and pregnancy. You may need to have the same tests more than once.
Specific blood tests your doctor may order include:
- Von Willebrand factor (vWF) antigen. This test determines the level of von Willebrand factor in your blood by measuring the vWF protein (antigen).
- Ristocetin cofactor activity. This analysis of your blood demonstrates how well the von Willebrand factor works in your clotting process. Ristocetin, which is an antibiotic, is used in this laboratory testing and when added to a sample of your blood causes a reaction in your blood that may indicate von Willebrand disease.
- Factor VIII clotting activity. This test shows whether you have abnormally low levels and activity of factor VIII.
- Von Willebrand factor multimers. This test evaluates the specific structure of von Willebrand factor in your blood, its protein complexes (multimers) and how its molecules break down. This information helps identify the type of von Willebrand disease that's present.
- Platelet function test (PFA-100). This test measures how efficiently platelets are functioning in your blood.
The results of some of these tests may not be available right away because the tests are conducted in a specialized laboratory. When these findings are analyzed together, your doctor can make a definite diagnosis.
If von Willebrand disease is present, your doctor may recommend that family members undergo the same or similar tests to determine if this condition runs in your family.
Jan. 02, 2014
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