(See also Overview of Platelet Disorders and Overview of Thrombocytopenia.)
Platelets are cells that circulate in the bloodstream and help blood clot. The blood usually contains about 140,000 to 440,000 platelets per microliter (140 to 440 × 109 per liter). When the platelet count falls below about 50,000 platelets per microliter of blood (50 × 109 per liter), bleeding can occur even after relatively minor injury. The most serious risk of bleeding, however, generally does not occur until the platelet count falls below 10,000 to 20,000 platelets per microliter of blood (10 to 20 ×109 per liter). At these very low levels, bleeding may occur without any recognized injury.
There are three main types of von Willebrand disease, all of which are inherited. The types differ on the degree of deficiency of the factor. People with the greatest deficiency have a higher risk of bleeding.
Symptoms of Von Willebrand Disease
Diagnosis of Von Willebrand Disease
Blood tests to measure platelet count and clotting
Other tests to rule out disorders that cause a low platelet count and bleeding
In most forms of von Willebrand disease, laboratory tests typically show that the platelet count is normal. One standard test of blood clotting (the prothrombin time [PT]) is usually normal while another standard test (partial thromboplastin time [PTT]) is usually prolonged.
Treatment of Von Willebrand Disease
Many people with mild von Willebrand disease never need treatment.
