Vitamin K1, or phylloquinone, is part of a group of similar fat-soluble vitamins. Phylloquinone is found in high amounts in leafy green vegetables and some fruits. It is a required cofactor involved in the gamma-carboxylation of glutamate residues of several proteins, most notably, the inactive forms of the coagulation factors prothrombin (factor II), factors VII, IX, and X, as well as protein S and protein C. Thus, vitamin K plays a critical role in haemostasis and acute deficiency is characterized by defective blood coagulation.
In neonates, low vitamin K levels in breast milk, inadequate placental transport, and hepatic immaturity leading to insufficient synthesis of coagulation proteins can result in the bleeding disorder haemorrhagic disease of the newborn. To minimize this risk, Vitamin K is commonly administered prophylactically immediately after birth. Other at-risk groups for vitamin K deficiency include those with insufficient dietary intake, malabsorption disorders, cystic fibrosis, cholestasis, and alcoholism, as well as liver and pancreatic disease. Several drugs such as coumarin anticoagulants and antibiotics have also been shown to interfere with vitamin K metabolism. In most cases, evaluation of vitamin K deficiency indirectly via prothrombin time (PT) and international normalised ratio (INR) is sufficient, these tests are typically prolonged in vitamin K deficiency.
High doses of vitamin K have not been shown to produce toxicity.
Lipids/Trace Metals
VITK
Wrap in foil.
Separate and freeze an aliquot of serum within 4 hours of collection. Aliquot to Lipids/Trace Metals- Freezer.
Gross haemolysis OK, gross lipemia reject, gross icterus OK
Only on frozen samples that have been separated within 4 hours of collection, stable frozen for 30 days.
3 weeks
3843