The Effects of Early Parenteral Amino Acids on Sick Premature Infants

To study the effects of early parenteral amino acid administration on body weight, fluid compartments and metabolic parameters during the first week of life in sick premature infants. Appropriate for gestational age, sick premature infants were randomized into two groups. Group A infants (n = 8, birth weight 1258 +/- 339 g) were supplemented with amino acids starting within 24 h of birth and advanced to 2.5 g/kg per day by day 3. Group G infants (n = 9, birth weight 1182 +/- 214 g) received amino acids starting on day 4 of life. Energy intake was comparable in the 2 groups. Amino acid concentrations and nitrogen balance studies were performed on day 3 of life. Total body water and extracellular water were measured on day 1 and 8 and change in intracellular volume was calculated. There was no significant difference between the 2 groups in terms of weight, intracellular volume change from day 1 to day 8 of life, despite a significant (P < 0.01) difference in protein intake. Plasma ammonia levels were comparable in the 2 groups, but plasma urea levels were significantly higher in group A vs. group G infants (7.2 +/- 3.4 mmol/L vs. 3.2 +/- 1.2 mmol/L respectively, P < 0.01). Nitrogen balance was positive in all group A infants and negative in group G infants. Nitrogen loss was inversely correlated with energy intake in group G infants (P < 0.05). The mean plasma amino acid concentrations in group A infants (compared to those of group G) were within previously reported ranges in older premature infants. There was no significant effect on body weight and redistribution of body fluid compartments in infants receiving amino acids early during the first week of life. Serum urea concentrations were significantly higher in infants receiving early amino acids. Nitrogen losses in infants who did not receive amino acids were inversely correlated with energy intake during the first 3 days of life.