Kvitaminfügg

Kvitaminfügg is a descriptive term used in nutrition and medicine to denote a state in which physiological processes depend on vitamin K for proper function. It is not a disease on its own but a characterization of systems that require adequate vitamin K status to operate correctly.

Biological basis: Vitamin K serves as a cofactor for γ-carboxylase enzymes, enabling gamma-carboxylation of glutamate residues in several proteins. In humans, this includes coagulation factors II (prothrombin), VII, IX, and X, as well as the anticoagulant proteins C and S, and bone/metabolic proteins such as osteocalcin and matrix Gla protein. Adequate vitamin K intake or recycling is thus essential for hemostasis and extracellular matrix regulation. A deficit or pharmacologic antagonism can impair carboxylation, reducing function of these proteins.

Clinical relevance: True vitamin K deficiency is uncommon in healthy adults but can occur with fat-malabsorption, severe liver disease, long-term broad-spectrum antibiotics, or very low dietary intake. Pharmacologic antagonists, such as warfarin, induce a functional Kvitaminfügg state by inhibiting vitamin K recycling, which alters coagulation status and requires monitoring. Newborns are particularly susceptible due to immature gut flora and low stores.

Diagnosis and management: Assessment involves coagulation tests (PT/INR) and, in some cases, measurement of undercarboxylated vitamin K–dependent proteins. Management depends on cause and may include dietary vitamin K, supplementation, or reversal strategies in anticoagulated patients.