Trace Element and Micronutrient Reference Laboratory

Scotland's specialised laboratory for trace elements and vitamins in health and disease

Vitamin K

Trace Elements

Vitamins

Specialised services

Vitamin K is a fat-soluble vitamins and exists in different forms. The main form vitamin K1 (Phylloquinone), is transported primarily by chylomicrons. Consequently serum vitamin K concentrations are influenced by plasma triglycerides concentration and reflect recent dietary intake. It is also associated with serum lipoproteins.

It is essential for synthesis of vitamin K dependent clotting factors (Prothrombin II, VII, IX& X). It is also required for the synthesis of other vitamin K dependent proteins such as protein C, protein S (anti coagulant activity), osteocalcin (bone formation), & protein Z. Vitamin K acts as a cofactor in the carboxylation of glutamic acid. This step confers calcium & phospholipid binding properties to the vitamin K dependent proteins, and so is essential for their functional activity.

Vitamin K deficiency, although rare, is not uncommon. Patients who are at risk of developing vitamin K deficiency are those on long-term broad-spectrum antibiotics or long-term hyperalimentation, and patients with chronic liver disease, biliary obstruction, or fat malabsorbtion are. Poor vitamin K status is associated with low bone mineral density. Oral anticoagulants such as warfarin act by antagonizing the metabolism of vitamin K.

No toxic manifestations have been noted on ingestion of large amounts of vitamin K over extended period of time. However administration of Menadione (not phylloquinone) may cause hyperbilirubinaemia and kernicterus in newborn.

Sample Requirements, Reference Values, & General Information