What is von Willebrand disease?
von Willebrand disease is the most common hereditary coagulation disorder. It arises from either qualitative or quantitative deficiency of von Willebrand factor, which is a protein that is required for platelet adhesion. There are 4 different types. Type 1 is the most common type. It is an Autosomal Dominant disorder. It decreases the levels of Von Willerbrand factors, which are proteins that are required for platelet adhesion. This decreased level of Von Willerbrand factors is going to result in problems with platelet adhesion.
When an injury occurs the sub-endothelial collagen becomes exposed. This leads to release of Von Willerbrand factors, which act as a linker molecule for platelet to bind to the collagen using Gp1b, which is located on the surface of platelets. Therefor, if there is no Von Willerbrand factors, that initial step for platelet adhesion cannot occur and the patient will not be able to stop bleeding and will present with Mucosal and Skin bleeding.
Signs and Symptoms for von Willerbrand disease:
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- Easy bruising,
- Bleeding Gums,
- Bleeding after surgery,
- Women may experience heavy menstrual periods and blood loss during childbirth.
Diagnosis for von Willebrand disease:
- History and Physical Examination; 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.
- 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.
Laboratory findings of von Willebrand disease:
- Increase Bleeding time is due to poor platelet adhesion so patient is not going to be able to seal off a damaged blood vessel quickly.
- Increased PTT this is very important because you need VWF to stabilize Coagulation Factor 8 and if you don’t have VWF you going to lose the stability of Factor 8 and that’s going to increase the PTT.
- Normal PT.
- Platelet count is Normal because the platelets are available they just cant form a cloth due to vWF deficiency.
- Abnormal Ristocetin Test. The idea here is that if you were to introduce Ristocetin to a patients platelets who has NORMAL amount of VWF, it would cause the platelets to all aggregate together. But in the case of VWF deficiency, since the patient is missing VWF, which is necessary for that initial step of adhesion then Ristocetin is not able to cause aggregation of the platelets.
Treatment for von Willebrand disease:
Treatment of von Willebrand disease focuses on stopping or preventing bleeding episodes, typically by using medications. With the right treatment, most people with von Willebrand disease can lead relatively normal, healthy lives.
- Desmopressin, which is a synthetic hormone, similar to the natural hormone vasopressin, and is given either by injection or more commonly, through a nasal spray. It controls bleeding by increasing the release of vWF and coagulation factor 8 from the endothelial cells.
- Another type of treatment is von Willebrand factor replacement therapy. This involves an infusion of concentrated von Willebrand factor and factor VIII into a vein in your arm.
- Contraceptives. These can be useful for controlling heavy bleeding during your menstrual periods. The estrogen hormones present in birth control pills can boost levels of von Willebrand factor and factor VIII activity.
References for von Willebrand disease: