Factor V is also known by which name?

Factor V is also known by which name?

• A. Tissue Thromboplastin
• B. Calcium
• C. Proaccelerin/Labile Factor
• D. Fibrinogen

Answer: (C)

Factor V’s alternate names reflect its role and its stability. It acts as a cofactor in the prothrombinase complex with Factor Xa on a phospholipid surface in the presence of calcium, helping convert prothrombin to thrombin. Historically, it was called proaccelerin because it accelerates the formation of thrombin from prothrombin. It’s also called labile factor because it is relatively unstable in vitro and loses activity with improper storage or handling. The other options correspond to different factors: tissue thromboplastin is Factor III, calcium is Factor IV, and fibrinogen is Factor I.

Factor V’s alternate names reflect its role and its stability. It acts as a cofactor in the prothrombinase complex with Factor Xa on a phospholipid surface in the presence of calcium, helping convert prothrombin to thrombin. Historically, it was called proaccelerin because it accelerates the formation of thrombin from prothrombin. It’s also called labile factor because it is relatively unstable in vitro and loses activity with improper storage or handling. The other options correspond to different factors: tissue thromboplastin is Factor III, calcium is Factor IV, and fibrinogen is Factor I.