Which coagulation factor does NOT require vitamin K for its production by the liver?

Coagulation factor VIII is indeed the correct answer as it does not require vitamin K for its production in the liver. Factor VIII is produced by endothelial cells and is considered a non-vitamin K dependent factor. While it is essential for the coagulation cascade, particularly for its role in stabilizing factor IXa, it does not require vitamin K for synthesis.

In contrast, factors VII, IX, and X are all vitamin K dependent. These factors need vitamin K for the post-translational modification of certain glutamic acid residues to gamma-carboxyglutamic acid (Gla). This modification is crucial for their functional activity because it allows these factors to bind calcium ions, which is necessary for their role in the coagulation cascade. Thus, a lack of vitamin K would lead to impaired synthesis of factors VII, IX, and X, resulting in increased bleeding risk.

Understanding these distinctions is important in clinical settings, especially when managing conditions related to bleeding disorders or vitamin K antagonism, such as with anticoagulants like warfarin.