Factor V


Molecular mass350.000 Da
SynthesisLiver, megakaryocytes, endothelial cells
Half life12 - 15 hours
Plasma concentration4 - 14 mg/l
Normal range60 - 120% or 0.6 - 1.2 U/ml

As cofactor in the prothrombinase complex, the activated form of factor V accelerates the activation of prothrombin to thrombin by factor Xa. The activation of factor V to factor Va can be effected by thrombin, factor Xa and certain snake venoms such as the Russell’s Viper Venom (RVV). Apart from the procoagulant effect of factor Va, factor V is involved as a cofactor together with protein S in the anticoagulant activity of activated protein C (APC).

Clinical significance

A homozygous hereditary factor V deficiency is very rare, whereas the heterozygous form is often observed. Apart from a true deficiency also altered factor V molecules (dysfunctional forms) exist. An acquired factor V deficiency occurs as a result of hepatic disease, DIC, hyperfibrinolytic conditions and chronic myeloid leukemia. Increased factor Va concentrations as a result of thrombin activation can be observed during phase I of DIC, in acute thrombosis, in postoperative phases and after inflammation.


  • Diagnosis and monitoring of DIC
  • Suspected hereditary factor V deficiency in hemorrhage of unknown cause
  • Suspected factor V inhibitors
  • Suspected pseudo homozygous APC Resistance due to combined FV deficiency and FV:Q506


  1. Roberts HR, Foster PA. Inherited disorders of prothrombin conversion. In Colman RW, Hirsh J, Marder VJ, Salzman EW: Hae-mostasis and Thrombosis. Basic Principles and Therapy, 2nd ed. Lippincott, Philadelphia, 162, 1987.
  2. Franchini M, Lippi G. Acquired factor V inhibitors: a systematic review. J Thromb Thrombolysis. 31(4):449-57, 2011.
  3. Ortel TL, Kane WH. Factor V. In: High KA, Roberts HR (eds.) Molecular Basis of thrombosis and hemostasis. New York, Marcel Dekker 119-146, 1995.
  4. Mann KG et al. Cofactor proteins in the assembly and expression of blood clotting enzyme complexes. Ann Rev Biochem 57, 915-956, 1988.
  5. Guasch JF et al. Molecular characterization of a type I quantitative factor V deficiency in a thrombosis patient that is pseudohomozygous for activated protein C resistance. Thromb Haemost 77, 252-257, 1997.
  6. Kalafatis M et al. Phenotype and genotype expression in pseudohomozygous factor V Leiden. The need for phenotype analysis. Arterioscler Thromb Vasc Biol 19, 336-342, 1999.
  7. Hoekema L et al. Human Factor Va1 and Factor Va2: Properties in the Procoagulant and Anticoagulant Pathways. Biochemistry 36, 3331-3335, 1997.
  8. Thalji N, Camire RM. Parahemophilia: new insights into factor v deficiency. Semin Thromb Hemost. Sep 39(6), 607-12, 2013.

Test kits

Matched-Pair Antibody set

ELISA Factor V