Phytomenadione or vitamin K1 plays a vital role in the production of vitamin K dependent coagulation factors, including factors II (prothrombin), VII, IX and X, and proteins C and S.
Vitamin K is found in green leafy vegetables and oils (soyabean, canola) and is synthesized by colonic bacteria.
Deficiency is frequent in newborns due to
- poor transmission of vitamin K across the placenta.
- paucity in breast milk, lack of gut bacteria and prematurity of liver function.
- Vitamin K deficiency may follow prolonged antibiotic use, parenchymal liver disease, prolonged total parenteral nutrition and malabsorption.
- The prevalence of late vitamin K deficiency bleeding in breastfed infants not given prophylaxis is 20 cases per 100,000 live births.
- Deficiency of vitamin K dependent factors leads to prolonged prothrombin and activated partial thromboplastin time.
Vitamin K is administered as a single subcutaneous dose of 1 mg at birth to prevent hemorrhagic disease of the newborn. Prophylaxis with vitamin K is widely practiced and safe. Larger doses of vitamin K (210 mg) can be given to treat symptomatic neonates who did not receive prophylaxis or have anticoagulant overdose; this is repeated till coagulation studies are normal. Fresh frozen plasma is administered if there is overt bleeding, or liver dysfunction is suspected.