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 establis hed. Parenteral Vitamin K prophylaxis remains the norm for the newborn infant in North America, though the recent controversy associating su ch prophylaxis with the incidence of childhood cancer has given new im petus to the consideration of oral prophylaxis. Oral preparations of v itamin K for the newborn infant may be desirable and clinical trials a re underway. The function and metabolism of vitamin K center around it s ability to serve as cofactor for the action of Vitamin K dependent c arboxylases present in most tissues. Hemorrhagic disease of the newbor n is a well described deficiency of the vitamin and has several differ ent 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 prod uction by intestinal bacteria is not a significant source of the vitam in for the newborn. The main source of vitamin K for the growing infan t is dietary intake, though human milk from mothers on ordinary diets is a very poor source of the vitamin. This probably accounts for the f act that breast-fed infants are at the greatest risk for hemorrhagic d isease. Assessment of coagulation factors is not a sensitive method to assess Vitamin K deficiency or sufficiency. Newer methods for assessi ng vitamin K status include direct assay of the vitamin concentration in plasma or serum, as well as measurement of abnormal prothrombin ass ociated with vitamin K deficiency (PIVKA-II). The specific antibody me thod is the best technique for measuring abnormal prothrombin. Finally , from a review of the most recent literature, it appears unlikely tha t parenteral Vitamin K prophylaxis increases the risk of childhood can cer.