Nitrogen sources for parenteral nutrition in the newborn infant.

Protein requirements for the preterm and term infant have been determined by a variety of methods. The parenteral protein needs of the very low birth weight infant are around 3 gm/kg/day and of the term infant approximately 2.2 gm/kg/day for maintenance of normal growth. These values are averages and may need to be modified for individuals depending upon a variety of potentially complicating factors. In this regard, many neonatologists recommend the provision of a maximum of 2 to 2.5 gm/kg/day of protein to newborns under most clinical situations. Whereas excessive administration of protein may result in adverse consequences, the tolerance of young infants to infusion of amino acid solutions is not well defined. Based upon animal studies of fetal amino acid utilization, the preterm infant may be capable of appropriately modifying its supply of amino acids over a relatively broad concentration range. It would appear that the supply of individual amino acids is adequately met by a number of amino acid solutions. The newer preparations appear to be more ideally suited to the special needs of the very low birth weight.