Donovan S M, Lönnerdal B, Atkinson S A
Department of Nutrition, University of California, Davis.
Acta Paediatr Scand. 1990 Oct;79(10):899-905. doi: 10.1111/j.1651-2227.1990.tb11350.x.
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.
先前的研究表明，与健康婴儿（13%）相比，感染康复期的足月儿对膳食尿素氮的保留率增加（40%），这可能是由于对氮的需求更高。由于低出生体重儿对氮的需求也很高，因此使用15N,15N-尿素对低出生体重儿的尿素氮生物利用度进行了研究。四名低出生体重儿（胎龄=30±2.2周[平均值±标准差]，出生体重=1.4±0.3千克）喂食富含15N,15N-尿素的配方奶。通过收集尿液和粪便进行了72小时的代谢平衡研究。通过凯氏定氮法对氮进行定量，通过气相色谱/质谱法对15N,15N-尿素进行定量。平均氮摄入量为489±32毫克/千克/天，氮吸收率为75%，氮保留率为62%。最大尿富集率为8%。15N,15N-尿素的累积排泄率为72%，保留率为28%。因此，低出生体重儿的尿素氮生物利用度似乎介于受损足月儿和正常足月儿之间。
