Von Willebrand disease

Introduction to von Willebrand disease Vascular hemophilia is a clinically common hereditary hemorrhagic disease whose pathogenesis is a mutation in the patient's von Willebrand factor (vWF) gene, resulting in a decrease in the amount or quality of plasma vWF. The incidence of vWD reported in foreign countries is about one thousandth. There is no statistical data in China. Because of the different types of vWD, clinical bleeding performance is very different, laboratory tests are more complicated than hemophilia, and changes in mild patients are not typical, often combined with medical history and clinical comprehensive judgment. basic knowledge The proportion of sickness: 0.00025% Susceptible people: children Mode of infection: non-infectious Complications: hematuria purpura

Cause of von Willebrand disease

Plasma VIII factor synthesis disorder (40%):

The factor VIII in normal human plasma is a glycoprotein with a molecular weight of up to 1 million to 2 million, containing low molecular weight and high molecular weight components, low molecular weight with clotting activity (VIII: C), and high molecular weight component with VIII factor. Related antigen (VIIIR: Ag) and VW factor (VIIIR: VWF), the synthetic sites of these three components, the genetic loci and their genetic patterns are controlled differently, and VIII:C is synthesized by liver spleen or monocyte. Under the control of X chromosome, VIII:C activity is reduced in hemophilia A, and it is recessive in sex chromosome. VIIIR:Ag and VIIIR:VWF are synthesized by endothelial cells, megakaryocytes and platelets, by autosomal inheritance, normal plasma. The VWF value is 10 mg/L, and its activity is produced by a series of plasma multimers. The molecular weight of the polymer is about 400,000 to 20 million. It exists in plasma, platelets and under the vascular endothelium, and the plasma VWF concentration is slightly decreased or high. Loss of molecular weight multimer selectivity can reduce platelet adhesion function, lack of these two components in VWD patients, or the molecular structure abnormalities of these two components, various physiological activities of VIII factor polymer Often, the VIII:C function also has a corresponding effect. VIIIR:Ag contains low, medium and high molecular weight polymers, which constitute different subtypes of VWD. The high molecular weight polymer of VIIIR:Ag binds to specific receptors of platelets. Platelets can be adhered to the subendothelial layer.

Genetic factors (25%):

According to the biochemical characteristics and function of factor VIIIR:Ag, VWD is divided into several types. Type I is more common, which shows the lack of factor VIIIR:Ag, the content of various polymers decreases, and all activities of factor VIII decrease, but the structure is normal. Type I is divided into autosomal recessive or dominant inheritance. The former is rare and the clinical manifestation is extremely serious. The plasma VIIIR:Ag disappears or is less than 0.1%, and can not be increased by injection of DDAVP. Type II: The amount of VIIIR:Ag is normal, but the structure of factor VIIIR:Ag polymer is abnormal, the amount of VIII:C is normal or slightly lower, and it is autosomal dominant. These patients lack high molecular weight and medium molecular weight polymers, type II. It is divided into several subtypes.

Vascular hemophilia prevention

1. Drugs that are frequently exposed to life, such as aspirin, dipyridamole, indomethacin, phenylbutazone, and dextran, are unsafe drugs for patients with bleeding disorders because they have the effect of inhibiting platelet aggregation and dilating blood vessels. Can increase bleeding.

2. Pay attention to diet: In the food selection, it is advisable to eat more fruits and vegetables containing more vitamin C, and pay attention to cooking methods to avoid coarse foods such as fish and bones, so as to avoid accidentally piercing the mucous membrane of the digestive tract, causing Bleeding.

3. Protect skin and mucous membranes: Patients should reduce irritation to skin and mucous membranes. When brushing your teeth, use a soft toothbrush or a cotton ball to avoid damage to the gums and cause bleeding. The clothes should be slightly wider. Avoid using sharp tools during activities. Try to avoid collisions between the limbs and external objects, prevent skin damage and subcutaneous bleeding.

4. If traumatic bleeding occurs at home, try to stop bleeding and limit joint activity at the bleeding site. The method of hemostasis has pressure dressing to stop bleeding, and is covered with a dry towel and a handkerchief in the wound; the finger pressure hemostasis method is used to press the end of the hemorrhage artery close to the heart with a finger, palm or fist, which can cut off the blood flow and achieve the purpose of temporarily stopping bleeding. If you can't reach complete hemostasis in a short time, you should go to the hospital urgently for treatment.

5. Patients should always have ice packs in their homes: patients with blood diseases have low body resistance and often have a fever. When you have a fever, your family should use the physical cooling method. You can put ice packs under the head and under the arm to achieve the purpose of cooling. You can also use cold water or alcohol to clean the bath to avoid cooling.

6. Prevent cross-infection at home: Cross-infection is a common cause of secondary infection of blood diseases. When relatives and friends suffer from respiratory infections or other infectious diseases, avoid contact with patients and keep the indoor environment clean.

Vascular hemophilia complications Complications, hematuria, purpura

The complications of this disease are:

1. Gingival bleeding, skin ecchymosis is common.

2. Occasionally hematuria, gastrointestinal bleeding and intracranial hemorrhage.

3. Joint bleeding is rare.

4. Hemorrhage after trauma or surgery is severe, and it is not easy to stop bleeding.

5. Women have more menstruation.

Symptoms of von Willebrand disease Common symptoms Gastrointestinal bleeding Hemorrhoids Hemorrhage Hemorrhagic tends Skin freckle Bowel joint swelling Postpartum hemorrhage Blood urinary bleeding Hemorrhage Menstrual volume

The incidence of this disease is higher than that of hemophilia. It is a common type of hereditary hemorrhagic disease. The clinical manifestations are bleeding tendency, hemorrhage has nasal discharge, gingival bleeding, gastrointestinal bleeding, extraction or surgery is not serious. Bleeding, women have more menstrual flow, often have a lot of bleeding after childbirth, often occur in childhood, with the increase of age, the severity of bleeding can be gradually reduced, autosomal recessive inheritance (type I) cases of severe bleeding, can be life-threatening, Joint bleeding often occurs after trauma, leaving no permanent joint deformity.

Examination of von Willebrand disease

1. Blood: red blood cells, white blood cells, platelet count and normal morphology.

2. Prolonged bleeding time or positive aspirin tolerance test.

3. The activated partial thromboplastin is prolonged or normal.

4. Platelet adhesion rate decreased or normal (64.2% ± 8.3%).

5. Factor VIII coagulation activity is measured or decreased.

6. The vWF antigen (vWF: Ag) is reduced or normal.

7. Positive blood vessel fragility test.

Diagnosis and diagnosis of von Willebrand disease

diagnosis

Diagnosis can be based on the cause, symptoms and related tests.

Differential diagnosis

(1) Platelet-type von Willebrand disease: This disease is a type of platelet dysfunction, and the affinity of platelet and plasma VW factor is increased, thus causing a deficiency of VW factor in plasma, causing vascular hemophilia-like performance. It needs to be distinguished. The disease often has thrombocytopenia. The platelet aggregation of patients with low concentration of ristocetin is enhanced, and there may be spontaneous platelet aggregation. If the platelet is added to normal people, the aggregation function returns to normal.

(2) Acquired von Willebrand disease: seen in systemic lupus erythematosus, lymphoproliferative disease, vascular proliferative disease and adrenal tumor, clinical manifestations except for the primary disease symptoms, bleeding tendency is similar to hereditary VWD, VW factor also Significantly reduced, in a few cases can find antibodies against VW factor, the disease needs to be distinguished from mild hemophilia A.

(C) platelet dysfunction disease: need to be distinguished from light vascular hemophilia, light VWD can be improved by the input of fresh plasma or cryoprecipitate, bleeding time and factor VIII related activities return to normal, and platelets Dysfunction is not effective.

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