Vitamin K Deficiency
Vitamin K deficiency is caused by insufficient intake of vitamin K1 or K2. A deficiency may also result from insufficient absorption, such as in Crohn's disease and cystic fibrosis. Vitamin K deficiency is of particular concern in newborns, as their sterile intestines are unable to synthesize vitamin K. This leads to a condition known as hemorrhagic disease of the newborn, which is characterized by increased PT and PTT but normal bleeding time. Similarly, prolonged broad spectrum antibiotic use may disturb gut flora, which again may lead to impaired synthesis of vitamin K and subsequent deficiency.