Primary deficiency of vitamin K is rare, but secondary deficiency may result from fat malabsorption syndrome. Prolonged use of antibiotics can destroy the intestinal bacteria that produce vitamin K, precipitating deficiency in individuals at risk. Newborn infants are born with a sterile intestinal tract and those who are breastfed, may run the risk of vitamin-K deficiency, since breast-milk production takes a few days to establish and breast milk is naturally low in this vitamin.
Vitamin K deficiency leads to a lowering of prothrombin level and increased clotting time of blood. This may lead to haemorragic conditions.
Inadequate intake of vitamin K by the mother may cause the haemorrhagic disease of the new born. Such infants have a low prothrombin level and recover rapidly when vitamin K is administered by injection.
Inadequate intestinal absorption of vitamin K may result from lack of bile in the intestine due to defective secretion of bile salts as in liver disorder, pyloric or intestinal obstruction and poor absorption due to diarrhea or dysentery. In vitamin K deficiency, the prothrombin content of blood is markedly decreased and the blood clotting time is considerably prolonged.