POSTMENSTRUAL AGE CORRELATES TO INDEXES OF PROTEIN-METABOLISM IN VERY-LOW-BIRTH-WEIGHT INFANTS

In 14 infants who were normal in weight for gestational age and 14 inf ants who were small for gestational age, the plasma essential amino ac id profiles and serum urea concentrations were studied between the 30t h and 46th weeks of postmenstrual age. All infants were of very low bi rth weight (<1,500 g) and were fed with fresh human milk fortified wit h 6 g freeze-dried human milk per 100 ml (mean protein intake 3.1 g/kg /day, mean energy intake 130 kcal/kg/day). With the exception of threo nine, all measured plasma essential amino acid concentrations increase d significantly with increasing postmenstrual age (appropriate for ges tational age infants: r = 0.861, p < 0.01; small for gestational age i nfants: r = 0.772, p < 0.001). No differences in this increase could b e found between the infants who were small or appropriate for gestatio nal age. The serum urea concentrations also increased with increasing postmenstrual age without differences between the study groups (approp riate for gestational age infants: r = 0.658, p < 0.01; small for gest ational age infants: r = 0.604, p < 0.05). The results indicate that v ery low birth weight infants of similar weights may have very differen t protein requirements, depending on their postmenstrual ages. Thus, p ostmenstrual age is of greater importance than birth weight when prote in nutrition is planned for very low birth weight infants.