title: Bioavailability of urea nitrogen for the low birthweight infant.
abstract: Previous studies have demonstrated increased retention (40%) of dietary urea nitrogen by term infants recovering from infection compared to healthy infants (13%), possibly due to a higher requirement for nitrogen. Since low birthweight infants also have a high requirement for nitrogen, the bioavailability of urea nitrogen was investigated in low birthweight infants using 15N,15N-urea. Four low birthweight infants (gestational age = 30 +/- 2.2 weeks [mean +/- SD], birthweight = 1.4 +/- 0.3 kg) were fed formula enriched with 15N,15N-urea. Metabolic balance studies (72 hours) were performed with urine and fecal collections. Nitrogen was quantitated by Kjeldahl analysis and 15N,15N-urea by gas chromatography/mass spectrometry. Mean nitrogen intake was 489 +/- 32 mg/kg/d, with 75% nitrogen absorption and 62% nitrogen retention. Maximum urinary enrichment was 8%. Cumulative 15N,15N-urea excretion was 72%, resulting in 28% retention. Thus the bioavailability of urea nitrogen for low birthweight infants appears to be intermediate between compromised and normal term infants.
authors: Department of Nutrition, University of California, Davis.
authors: S M
authors: SM
authors: Donovan
authors: B
authors: B
authors: Lönnerdal
authors: S A
authors: SA
authors: Atkinson
mesh_terms: D001682:Biological Availability; D005260:Female; D006801:Humans; D007225:Infant Food; D007230:Infant, Low Birth Weight / Q000378:metabolism*; D007231:Infant, Newborn; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea; D009584:Nitrogen