Vitamin K

Dr Dan J Bell and Dr Craig Hacking et al.

Vitamin K is a family of fat-soluble vitamins essential for normal blood-clotting function and comprises two vitamers that are found naturally: phytomenadione (also known as phylloquinone or K1) and menaquinone (or K2).

Menaquinone is synthesised by normal flora in the intestine although the amount produced in vivo in the human gut is likely negligible. Vitamin K serves as a coenzyme for the clotting factors II, VII, IX and X. Warfarin inhibits vitamin K by preventing its enzymatic reactivation. 

Pathological manifestations are rare. Hypovitaminosis K can lead to jaundice and anaemia in the neonate. 

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Article information

rID: 49232
Section: Pathology
Synonyms or Alternate Spellings:
  • Vitamin K1
  • Vitamin K2
  • Phytomenadione
  • Phylloquinone
  • Menaquinone

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