Threonine Requirement in Neonates Receiving Total Parenteral Nutrition (TPN)

Current neonatal threonine (THR) enteral requirement is 87 mg·kg‐1·d‐1. The THR requirement of the parenterally (TPN) fed human neonate has never been experimentally determined. Concentrations of THR in commercially available TPN solutions are derived from concentrations in cord blood, plasma amino acid profile during TPN feeding, or human milk, and are 30 to 80% higher than the enteral requirement. We showed in piglets that the neonatal TPN requirement for THR was 55% lower than the enteral requirement. Our objective was to determine the human neonatal TPN requirement for THR in post‐surgical neonates using the indicator amino acid oxidation technique with L[1–13C]phenylalanine. Neonates were randomized to receive one of twelve THR intakes ranging from 10 to 100 mg· kg‐1·d‐1. Preliminary data indicate a mean THR requirement between 30 and 40 mg·kg‐1·d‐1, only 30% of the THR concentration in the lowest THR containing TPN solution. We conclude that the THR requirement for TPN fed human neonates is significantly lower than the THR present in current TPN solutions and the recommended intake for orally fed infants. High THR intakes are a concern; THR is potentially neurotoxic and neonates are unable to oxidize excess