Intravenous nitrogen and energy intakes required to duplicate in utero nitrogen accretion in prematurely born human infants

Abstract

In order to determine the intravenous energy and nitrogen intakes required to achieve intrauterine rates of nitrogen accretion and growth, 30 studies were completed in 22 premature infants who were provided with various intakes of amino acids and energy (glucose +/- lipid) by peripheral vein infusion. At constant nitrogen intake, increasing energy intake (as lipid) from 50 to 80 nonprotein kcal/kg/day resulted in significant increases in nitrogen retention and weight gain. Increasing nitrogen intake from 494 to 655 mg/kg/day at constant low energy intake (mean = 53 kcal/kg/day) had no effect on nitrogen retention or weight change; however, at higher energy intakes (mean = 81 kcal/kg/day) increasing nitrogen intake correlated significantly with increasing nitrogen retention. At energy intakes greater than 70 kcal/kg/day the major determinant of nitrogen retention was nitrogen intake. When energy intake was greater than 70 kcal/kg/day, the infusion of nitrogen providing 430 to 560 mg/kg/day (2.7 to 3.5 gm protein/kg/day) resulted in the duplication of intrauterine nitrogen accretion rates.