American Medical Association Family Medical Guide - American Medical Association [371]
Von Willebrand’s Disease
Von Willebrand’s disease is the most common inherited bleeding disorder. People who have this disorder have a defect or shortage of a blood protein called von Willebrand factor, which helps platelets (cell fragments that enable blood to clot) function normally. When a person who has von Willebrand’s disease is cut or injured, the blood does not clot normally to seal the damaged blood vessels. Severe bleeding can occur during routine dental care, from a sports-related injury, or during surgery or childbirth.
Von Willebrand’s disease is more common than hemophilia (see previous article), although hemophilia is the better known blood disorder. Von Willebrand’s disease affects about 1 percent of people in the United States. Although its effects are usually mild, about 20 percent of people who have the disorder experience moderate or severe bleeding. The defective gene responsible for the disorder can be inherited from either parent. Unlike hemophilia, which affects mostly males, von Willebrand’s disease affects males and females in equal numbers. The disorder poses a bigger health problem for women than it does for men because one of its primary symptoms, heavy menstrual bleeding, can be misdiagnosed as a gynecological problem rather than a bleeding disorder, causing a delay in treatment.
Symptoms
Symptoms of von Willebrand’s disease usually appear in childhood, as soon as a child becomes active, and may decrease with age. People who have von Willebrand’s disease bruise easily, have recurring nosebleeds, and often bleed heavily from the gums after brushing their teeth or during routine dental care. Rarely, bleeding after an injury also can occur inside the brain, which can be life-threatening.
Women who have the disorder have intense and prolonged menstrual periods that can last for weeks or months without stopping. Such uninterrupted bleeding can cause severe anemia (see page 610) and can interfere with a woman’s ability to get pregnant or carry a pregnancy to full term. Women who have the disorder also have an increased risk of potentially severe hemorrhaging immediately after childbirth.
Diagnosis
If you have symptoms of a bleeding disorder, your doctor will probably recommend that you see a hematologist (a doctor who specializes in treating diseases of the blood) to get an accurate diagnosis. After performing a physical examination and obtaining a detailed health history, the hematologist will ask you about any episodes of bleeding in close relatives. He or she will then order blood tests that measure platelet function, clotting factor function, and the levels of certain clotting factors in your blood. These tests are very sensitive and can be made inaccurate by several variables, including the menstrual cycle, the use of aspirin or other nonsteroidal anti-inflammatory drugs that thin the blood, exercise, stress, and a cold environment. For this reason, the tests may need to be repeated before the doctor can confirm the diagnosis.
Treatment
There is no cure for von Willebrand’s disease. Mild forms of the disease usually require no treatment other than routine instruction in first aid. For example, you may be shown how to apply pressure with your fingers to help a wound stop bleeding. For moderate or severe bleeding problems, a hematologist may prescribe a hormonal drug called desmopressin, which triggers the body to release the von Willebrand factor. The hormone can be taken by injection or in a nasal spray. People who do not respond to treatment with desmopressin may be given a transfusion of concentrated clotting factors (including von Willebrand factor) called cryoprecipitate.
Women who have heavy bleeding during menstrual periods may benefit from taking birth-control pills. The same hormones that are in birth-control pills can also be rubbed onto the skin or applied as a patch. For unknown reasons, pregnancy often reduces the symptoms of the