Factor VIII (anti-hemophilic globulin A)
Last reviewed: 23.04.2024
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The reference values (norm) of the activity of factor VIII in blood plasma are 60-145%.
The plasma clotting factor VIII - anti-hemophilic globulin A - circulates in the blood in the form of a complex of three subunits, designated VIII-k (coagulating unit), VIII-Ar (the main antigen marker) and VIII-PV (von Willebrand factor bound to VIII-Ar ). It is believed that VIII-FV regulates the synthesis of the coagulation part of anti-hemophilic globulin (VIII-k) and participates 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 + ). Hemophilia A - revealed 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%.
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