Von Willebrand's Disease
Von Willebrand's disease is a hereditary deficiency or abnormality of the von Willebrand factor in the blood, a protein that affects platelet function.
The von Willebrand factor is found in plasma, platelets, and the walls of blood vessels. When the factor is missing or defective, platelets cannot adhere to the vessel wall at the site of an injury. As a result, bleeding does not stop as quickly as it should.
Symptoms and Diagnosis
Often, a person with von Willebrand's disease has a parent who has a history of bleeding problems. Typically, a child bruises easily or bleeds excessively after a cut, tooth extraction, or surgery. A young woman may have increased menstrual bleeding. Bleeding may worsen at times. On the other hand, hormonal changes, stress, pregnancy, inflammation, and infections may stimulate the body to increase production of the von Willebrand factor and temporarily improve the capacity of platelets to stick to the blood vessel wall and stop bleeding.
Laboratory tests typically show that the bleeding time is abnormally long. Bleeding time is the amount of time that elapses before bleeding stops after a small cut is made on the forearm. Doctors may order tests that measure the amount of von Willebrand factor in the blood. Because the von Willebrand factor is 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.
Treatment
Many people with von Willebrand's disease never need treatment. If excessive bleeding occurs, a transfusion of concentrated blood clotting factors containing von Willebrand factor may be given. For some mild forms of the disease, drug treatment with desmopressin may be given to increase the amount of the von Willebrand factor long enough for surgery or dental procedures to be performed without transfusions.
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