Plasma concentrations of vitamin K1 and PIVKA-II in bottle-fed and breast-fed infants with and without vitamin K prophylaxis at birth.

Plasma vitamin K1 and proteins induced by vitamin K absence (PIVKA) were assayed simultaneously 1-4 days and 29-35 days after delivery in three groups of infants: breast-fed not receiving vitamin K at birth (n = 12), bottle-fed without vitamin K administration at birth (n = 7) and breast-fed receiving 1 mg vitamin K1 administered by intramuscular injection at birth (n = 13). The bottle-fed infants had a significantly higher vitamin K1 plasma level than breast-fed infants who did not receive vitamin K1 at birth. Extremely high levels of vitamin K were obtained 1-4 days after intramuscular administration. At the age of 1 month, breast-fed infants had the same plasma vitamin K1 concentration whether or not they had received vitamin K1 supplements. Decarboxy prothrombin (PIVKA-II) a reliable indicator of biochemical vitamin K deficiency, was found in 5 out of 12 breast-fed and in 2 out of 6 bottle-fed infants who had not received supplemental vitamin K1 after birth. In a separate study, we followed up to 90 days after birth a larger group if infants. PIVKA-II was found with significantly greater frequency in breast-fed infants receiving no vitamin K than in breast-fed infants receiving 1 mg vitamin K intramuscularly at birth, or in bottle-fed infants without extra vitamin K1. These data form a strong argument for routine vitamin K prophylaxis after birth for all breast-fed infants. The optimum dose and manner of administration require further study.