THE IMPORTANCE OF VITAMIN-K AS A NUTRIENT DURING THE FIRST YEAR OF LIFE

The efficacy for Vitamin K prophylaxis in the newborn is well established. Parenteral Vitamin K prophylaxis remains the norm for the newborn infant in North America, though the recent controversy associating such prophylaxis with the incidence of childhood cancer has given new impetus to the consideration of oral prophylaxis. Oral preparations of vitamin K for the newborn infant may be desirable and clinical trials are underway. The function and metabolism of vitamin K center around its ability to serve as cofactor for the action of Vitamin K dependent carboxylases present in most tissues. Hemorrhagic disease of the newborn is a well described deficiency of the vitamin and has several different presentations, the most serious of which occurs after two weeks of age. On the other hand, vitamin K deficiency is probably not a factor in the etiology of intraventricular hemorrhage in premature infants. Vitamin K is not readily transported across the placenta, and its production by intestinal bacteria is not a significant source of the vitamin for the newborn. The main source of vitamin K for the growing infant is dietary intake, though human milk from mothers on ordinary diets is a very poor source of the vitamin. This probably accounts for the fact that breast-fed infants are at the greatest risk for hemorrhagic disease. Assessment of coagulation factors is not a sensitive method to assess Vitamin K deficiency or sufficiency. Newer methods for assessing vitamin K status include direct assay of the vitamin concentration in plasma or serum, as well as measurement of abnormal prothrombin associated with vitamin K deficiency (PIVKA-II). The specific antibody method is the best technique for measuring abnormal prothrombin. Finally, from a review of the most recent literature, it appears unlikely that parenteral Vitamin K prophylaxis increases the risk of childhood cancer.