Albumin synthesis in preterm infants on the first day of life studied with [1-C]leucine

Bunt JE, Rietveld T, Schierbeek H, Darcos Wattimena JL, Zimmermann LJ, van Goudoever JB. Albumin synthesis in preterm infants on the first day of life studied with [1-C]leucine. Am J Physiol Gastrointest Liver Physiol 292: G1157–G1161, 2007. First published January 18, 2007; doi:10.1152/ajpgi.00300.2006.—Albumin is the major binding protein in the human neonate. Low production of albumin will lower its transport and binding capacity. This is especially important in preterm infants, in whom albumin binds to potentially toxic products such as bilirubin and antibiotics. To study the metabolism of plasma albumin in preterm infants, we administered a 24-h constant infusion of [1-C]leucine to 24 very low birth weight (VLBW) infants (28.4 0.4 wk, 1,080 75 g) on the first day of life. The caloric intake consisted of glucose only, and therefore amino acids for albumin synthesis were derived from proteolysis. The fractional synthesis rate (FSR) of plasma albumin was 13.9 1.5%/day, and the absolute synthesis rate was 148 17 mg kg 1 day . Synthesis rates were significantly lower (P 0.03) in infants showing intrauterine growth retardation. Albumin synthesis increased with increasing SD scores for gestation and weight (P 0.05). The FSR of albumin tended to increase by 37% after administration of antenatal corticosteroids to improve postnatal lung function (P 0.09). We conclude that liver synthetic capacity is well developed in VLBW infants and that prenatal corticosteroids tend to increase albumin synthesis. Decreased weight gain rates in utero have effects on protein synthesis postnatally.