Plasma L-arginine concentrations in premature infants with necrotizing enterocolitis

Objective: To determine whether L-arginine concentrations (the substrate for nitric oxide synthesis) are lower in premature infants in whom necrotizing enterocolitis (NEC) develops than in unaffected infants. Methods: We measured arginine and nutritional intake, plasma arginine, glutamine, total amino acids, and ammonia concentrations in 53 premature infants (mean gestational age +/- SD: 27 +/- 1.7 weeks) at risk of NEC. Measurements were done on days 3, 7, 14 and 21 and just before treatment in infants with NEC. Results: Necrotizing enterocolitis developed in 11 infants between postnatal days 1 and 26. On day 3, plasma arginine concentrations were decreased compared with normal published values (mean +/- SE, 41 mu mol/L +/- 4). Arginine concentrations increased with day of life of measurement (p < 0.001) and arginine intake (p < 0.001). Plasma arginine concentrations were significantly lower at the time of diagnosis in infants with NEC compared with control subjects, even after adjusting for arginine intake and day of life (p = 0.032). Plasma glutamine and total amino acid concentrations were not significantly different in infants with NEC compared with control subjects. Plasma ammonia concentrations were elevated on day 3 (mean +/- SE, 72 +/- 3.3 mu mol/L) and decreased with postnatal age (p < 0.001) and increasing plasma arginine concentrations (p < 0.001). Conclusion: Plasma arginine concentrations are decreased at the time of diagnosis in premature infants with NEC. The potential benefit of arginine supplementation in the prevention of the disease deserves evaluation.