VITAMIN K DEFICIENCY

lack of vitamin K in the body, resulting in impaired clotting of the blood and internal bleeding. Blood clotting is delayed or prevented because vitamin K is unavailable to act as a cofactor in the synthesis of the four required coagulation factors (especially prothrombin). Vitamin K deficiency is seldom naturally encountered in higher animals because the vitamin is usually adequately supplied in the diet, besides being synthesized by intestinal bacteria. In humans, deficiency may occur following the administration of certain drugs that inhibit the growth of the vitamin-synthesizing bacteria or as a result of constitutional disorders affecting the production or flow of bile, which itself is necessary for the intestinal absorption of vitamin K. In newborn infants, the absence of large intestinal bacteria coupled with the absence of body stores of vitamin K may result in a condition known as hemorrhagic disease of the newborn, which can be prevented by the administration of vitamin K to the infant shortly after birth, or to the mother during labour.