Editing Coagulation (section)

====Vitamin K====
[[Vitamin K]] is an essential factor to the hepatic [[gamma-glutamyl carboxylase]] that adds a [[carboxyl]] group to [[glutamic acid]] residues on factors II, VII, IX and X, as well as [[Protein S]], [[Protein C]] and [[Protein Z]]. In adding the gamma-carboxyl group to glutamate residues on the immature clotting factors, Vitamin K is itself oxidized. Another enzyme, ''[[Vitamin K epoxide reductase]]'' (VKORC), reduces vitamin K back to its active form. Vitamin K epoxide reductase is pharmacologically important as a target of anticoagulant drugs [[warfarin]] and related [[coumarin]]s such as [[acenocoumarol]], [[phenprocoumon]], and [[dicumarol]]. These drugs create a deficiency of reduced vitamin K by blocking VKORC, thereby inhibiting maturation of clotting factors. Vitamin K deficiency from other causes (e.g., in [[malabsorption]]) or impaired vitamin K metabolism in disease (e.g., in [[liver failure]]) lead to the formation of PIVKAs (proteins formed in vitamin K absence), which are partially or totally non-gamma carboxylated, affecting the coagulation factors' ability to bind to phospholipid.<ref name="Paulus">{{Cite journal |last=Paulus |first=MC |last2=Drent |first2=M |last3=Kouw |first3=IWK |last4=Balvers |first4=MGJ |last5=Bast |first5=A |last6=van Zanten |first6=ARH |date=1 July 2024 |title=Vitamin K: a potential missing link in critical illness-a scoping review. |journal=Critical Care |volume=28 |issue=1 |page=212 |doi=10.1186/s13054-024-05001-2 |pmc=11218309 |pmid=38956732 |doi-access=free}}</ref>