Increased parenteral amino acid administration to extremely low-birth-weight infants during early postnatal life

Background: Early administration of parenteral amino acids to infants with extremely low birth weight (birth weight less than or equal to 1,000 to has been encouraged to foster growth. However, excessive intravenous intake of amino acids may cause metabolic acidosis and uremia in extremely low, births weight infants. The hypothesis for this study was that extremely low birth weight infants would tolerate slightly increased early postnatal parenteral amino acid administration and benefit. Methods: The peak daily parenteral amino acid dosage was increased from 3 g/kg (standard group) to 4 g/kg (modified group). The corrected parenteral amino acid dosage was computed to account for enteral protein intake and keep the combined daily intravenous amino acid and enteral protein intake at or below 3 g (.) kg(-1) d(-1) in the standard group and 4 g (.) kg(-1 .) d(-1) in the modified group. The primary outcome measure was plasma bicarbonate concentration as an indicator of acid-base status. Data were collected for patient demographics, nutritional intake. serum bicarbonate and serum urea nitrogen concentrations. and outcome. Results: The corrected parenteral amino acid intake of the modified group was 16% greater at postnatal week 1 (3.30 +/- 0.83 g (.) kg(-1 .) d(-1), mean +/-1 SD) and 18% greater (3.86 +/- 0.94 g (.) kg(-1) (.) d(-1)) at postnatal week 2 than the parenteral amino acid intake of the standard group. In the modified group, the mean serum bicarbonate concentration was 19.1 +/- 1.8 mEq/dL at week 1 and 23.9 +/- 2.9 mEq/dL at week 2, with no difference between the groups. At week 1, serum urea nitrogen concentrations were the same in both groups. The mean serum urea nitrogen concentration of the modified group at postnatal week 2 (18.2 +/- 8.8 mg/dL) was unchanged from postnatal week 1, but was greater than that of the standard group at postnatal week 2. Weight gain was the same in both groups. Corrected parenteral amino acid intake at postnatal week 1 correlated directly with weight gain from birth to postnatal week 2 (P < 0.03) in both groups. Conclusions: Infants with extremely low birth weight tolerated parenteral amino acid intake of approximately 4 g (.) kg(-1) (.) d(-1). Mild increases of mean serum urea nitrogen concentration and mean weight gain were associated with increased parenteral amino acid administration without significant acidosis.