Factor V

Factor V is a blood-clotting protein that helps form stable clots. Having normal factor V means typical clotting; low factor V causes a rare bleeding disorder with easy bruising and nosebleeds. A common mutation (Factor V Leiden) makes factor V resistant to breakdown, increasing risk of abnormal clots (venous thrombosis). Testing identifies abnormalities; management ranges from observation to anticoagulation for high-risk individuals.

The V factor is nicotinamide adenine dinucleotide (NAD), a bacterial growth factor required by species such as Haemophilus influenzae. As a coenzyme, it participates in redox reactions and cellular metabolism. In laboratory diagnosis, V factor dependence is used with X factor (hemin) to identify organisms; supplementing cultures with NAD or NAD-producing colonies enables satellite growth of V-dependent bacteria.

Factor V is also called proaccelerin or labile factor. It’s a plasma glycoprotein that acts as a cofactor in the coagulation cascade for the prothrombinase complex; when activated by thrombin it becomes Factor Va. Deficiency causes bleeding (parahemophilia), while certain mutations (Factor V Leiden) increase the risk of thrombosis.

Factor V protein is made by the liver and, if low from reversible causes (infection, liver injury, certain drugs, consumption), levels can recover once the cause is treated. Congenital factor V deficiency is lifelong and managed medically. Factor V Leiden is a genetic mutation and does not go away — it remains present for life and increases clotting risk.

Yes. Most people with Factor V (Factor V Leiden) live long, healthy lives. The mutation increases risk of venous blood clots—heterozygotes have lower risk, homozygotes higher—so management involves treating clots, using anticoagulants when needed, and preventive measures during surgery, pregnancy, or with estrogen use. Healthy lifestyle, avoiding smoking, staying hydrated and regular medical follow-up reduce risk.

Factor V abnormalities can affect clotting but typically cause venous thrombosis rather than classic ischemic stroke. The common Factor V Leiden mutation increases risk of deep vein thrombosis and pulmonary embolism; its association with arterial stroke is weak, though it may slightly raise risk in younger people with other factors. Factor V deficiency causes bleeding, not clotting-related strokes.