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Bioavailability of Urea Nitrogen for the Low Birthweight Infant
Author(s) -
DONOVAN SHARON M.,
LÖNNERDAL BO,
ATKINSON STEPHANIE A.
Publication year - 1990
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1990.tb11350.x
Subject(s) - urea , bioavailability , nitrogen balance , kjeldahl method , nitrogen , medicine , urine , excretion , zoology , chemistry , biochemistry , biology , pharmacology , organic chemistry
. 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 15 N, 15 N‐urea. Four low birthweight infants (gestational age = 30 ±2.2 weeks [mean ± SD, birthweight = 1.4 ±0.3 kg) were fed formula enriched with 15 N, 15 N‐urea. Metabolic balance studies (72 hours) were performed with urine and fecal collections. Nitrogen was quantitated by Kjeldahl analysis and 15 N, 15 N‐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 15 N, 15 N‐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.