blood disorders
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, Clotting 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. Doctors usually order tests that measure the amount ofvon Willebrand factorin the blood and determine how well thevon Willebrand factorfunctions. Becausevon Willebrand factoris the protein that carries an important clotting factor (factor VIII) in the blood, the level of factor VIII in the blood may also be decreased (resulting in a prolonged PTT test). 