Factor VIII( anti-hemophilic globulin a)

Reference values ​​of the activity of factor VIII in blood plasma - 60-145%.

Factor VIII of plasma clotting - antihemophilic globulin A - circulates in the blood in the form of a complex of three subunits, denoting

VIII-k( coagulating unit), VIII-Ar( the main antigenic marker) and VIII-PV( von Willebrand factor,associated with VIII-Ar).It is believed that VIII-FV regulates the synthesis of the coagulation part of anti-hemophilic globulin( VIII-k) and is involved in vascular-platelet hemostasis. Factor VIII is synthesized in the liver, spleen, endothelial cells, leukocytes, kidneys and takes part in the first phase of plasma hemostasis.

Determination of factor VIII plays a crucial role in the diagnosis of hemophilia A. The development of hemophilia A is due to the inherent deficiency of factor VIII.In the blood of patients with factor VIII there is no( hemophilia A-) or it is in a functionally inferior form, which can not take part in blood clotting( hemophilia A +).Haemophilia A-detected in 90-92% of patients, haemophilia A + - in 8-10%.When hemophilia, the content of VIII-k plasma is sharply reduced, and the concentration of VIII-PV in it is within the normal range. Therefore, the duration of hemorrhage in hemophilia A is within the regulatory limits, and with von Willebrand disease is increased.

Hemophilia A is a hereditary disease, but in 20-30% of patients a positive family history is not traced. Therefore, the determination of the activity of factor VIII is of great diagnostic value. Depending on the level of activity of factor VIII, the following clinical forms of hemophilia A are divided: extremely severe - factor VIII activity up to 1%;heavy - 1-2%;average severity - 2-5%;light( subhemophilia) - 6-24%.

Approximately one third of "carriers" of hemophilia A have activity of factor VIII ranging from 25 to 49%.In patients with mild form and "carriers" of hemophilia A, clinical manifestations of the disease occur only after injuries and surgical interventions.

The minimum hemostatic level of factor VIII activity in the blood for operations is 25%, with a lower content the risk of postoperative bleeding is extremely high. The minimum hemostatic level of factor VIII activity in the blood for stopping bleeding is 15-20%, with a lower content the stop of bleeding without the introduction of a factor VIII patient is impossible. With von Willebrand's disease, the minimum hemostatic level of factor VIII activity for stopping bleeding and for the operation is 25% [Ogston D., Bennett B., 1977].

With ICE, starting with stage II, there is a distinct decrease in factor VIII activity due to consumption coagulopathy. Severe liver disease can lead to a decrease in the content of factor VIII in the blood. The content of factor VIII decreases with von Willebrand's disease, as well as in the presence of specific antibodies to factor VIII.

Factor VIII activity is significantly increased after splenectomy.

In clinical practice, it is very important to differentiate hemophilia and von Willebrand's disease. In Table. The parameters of the coagulogram for these two diseases are presented.

Table Indicators of coagulogram in hemophilia and von Willebrand's disease