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Factor VII (proconvertin)
Last reviewed: 06.07.2025
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Reference values (norm) of factor VII activity in blood plasma are 65-135%.
Factor VII (proconvertin or convertin) is an α 2 -globulin and is synthesized in the liver with the participation of vitamin K. It is mainly involved in the formation of tissue prothrombinase and the conversion of prothrombin into thrombin. Its half-life is 4-6 hours (the shortest half-life among coagulation factors).
Congenital proconvertin deficiency
Congenital deficiency of factor VII causes the development of Alexander disease, an autosomal recessive disorder associated with a defect in the synthesis of proconvertin.
This pathology is characterized by a mixed type hemorrhagic syndrome - hematoma-microcirculatory. The leading clinical signs are: melena, ecchymosis and petechiae, bleeding from the umbilical wound, cephalohematoma. These typical manifestations occur only when the content of proconvertin in the blood is less than 5% of the norm, which is extremely rare in clinical practice.
Laboratory tests reveal an increase in blood clotting time (with normal bleeding time and platelet count), an increase in PT and APTT. To finally confirm the diagnosis, the proconvertin content in the blood serum should be determined (normally 65-135%).
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Treatment
Bolus administration of a concentrated preparation of prothrombin complex, which includes factor VII, at 15-30 U/kg intravenously.
For newborns, the doses of factor VII administration have not been worked out, but should not exceed 70 U. If necessary, intravenous administration can be repeated. More effective for this coagulopathy is intravenous infusion of an anti-inhibitor coagulant complex (Feiba T1M 4 Immuno) at a dose of 50 to 100 U 2 times a day or NovoSeven (INN: Eptacog alpha activated) at a dose of 20 to 70 mcg/kg at intervals of 3 hours.
Acquired proconvertin deficiency
Acquired forms of hypoproconvertinemia are possible in patients with liver damage, as well as as a result of the action of indirect anticoagulants. A decrease in the activity of proconvertin in the blood plasma is noted in patients with viral hepatitis, liver cirrhosis, acute alcoholic hepatitis, chronic persistent hepatitis. In patients with liver cirrhosis, a clear connection is observed between a decrease in the level of proconvertin and the severity of the process. Due to the short half-life, a decrease in the activity of proconvertin is the best marker for the development of liver failure, the onset of which can be tracked literally by the hour, examining the activity of proconvertin in the blood.
The minimum hemostatic level of factor VII activity in the blood for performing operations is 10-20%; at a lower content, the risk of developing postoperative bleeding is extremely high. The minimum hemostatic level of factor VII activity in the blood for stopping bleeding is 5-10%; at a lower content, stopping bleeding without administering factor VII to the patient is impossible.
In DIC syndrome, starting from stage II, a clear decrease in factor VII activity is noted due to consumption coagulopathy.
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