Relationship between arginine intake in parenteral nutrition and preterm neonatal population plasma arginine concentrations: a systematic review

CONTEXT: Very preterm neonates (VPNs) are unable to digest breast milk and therefore rely on parenteral nutrition (PN) formulations. This systematic review was prepared following PRISMA-P 2015 guidelines. For the purpose of this review, desirable mean plasma arginine concentration is defined as ≥80 micromoles/L. OBJECTIVE: The review was performed to answer the following research question: “In VPNs, are high amounts of arginine in PN, compared with low amounts of arginine, associated with appropriate circulating concentrations of arginine?” Therefore, the aims were to 1) quantify the relationship between parenteral arginine intakes and plasma arginine concentrations in PN-dependent VPNs; 2) identify any features of study design that affect this relationship; and 3) estimate the target parenteral arginine dose to achieve desirable preterm plasma arginine concentrations. DATA SOURCES: The PubMed, Scopus, Web of Science, and Cochrane databases were searched regardless of study design; review articles were not included. DATA EXTRACTION: Only articles that discussed amino acid (AA) intake and measured plasma AA profile post PN in VPNs were included. Data were obtained using a data extraction checklist that was devised for the purpose of this review. DATA ANALYSIS: Twelve articles met the inclusion criteria. The dose–concentration relationship of arginine content (%) and absolute arginine intake (mg/(kg × d)) with plasma arginine concentrations showed a significant positive correlation (P < 0.001). CONCLUSION: Future studies using AA solutions with arginine content of 17%–20% and protein intakes of 3.5–4.0 g/kg per day may be needed to achieve higher plasma arginine concentrations.