Phenylalanine, Methionine and Histidine Requirements in TPN Fed Neonates

This study measures the nutritional needs of premature newborns receiving all their nutrition through an IV (called total parenteral nutrition, or TPN). Specifically, it looks at how much of three amino acids — phenylalanine, methionine, and histidine — preterm babies need to grow and develop properly. Knowing this helps doctors provide better nutrition for premature infants. You may be eligible if... - Your baby is premature, born at 28 weeks gestation or later - Your baby is stable, growing, and receiving at least 90% of nutrition through TPN - Your baby is 28 days old or younger - Your baby has a birth weight and length appropriate for gestational age - Your baby has been medically stable (normal blood results, no fever or infection) - If your baby had surgery, it has been at least 3 days since the operation You may NOT be eligible if... - Your baby is on mechanical ventilation, low-flow oxygen, or CPAP - Your baby is small for gestational age - Your baby is on medications that affect protein metabolism - Your baby has a documented infection or fever - Your baby is receiving more than 10% of protein intake through feeds Talk to your baby's doctor to see if this trial is right for your family.