Plasma and urine amino acid pattern in preterm infants on enteral nutrition: impact of gestational age

Amino Acids. 2010 Mar;38(3):959-72. doi: 10.1007/s00726-009-0305-0. Epub 2009 May 26.


Plasma and urine amino acids were determined by ion-exchange chromatography in 80 healthy preterm infants divided into three groups: (1) 23 0/7-28 0/7, (2) 28 1/7-32 0/7 and (3) 32 1/7-35 0/7 weeks of gestation. Samples were collected from days 5 to 57 of life, when infants were exclusively orally fed. Infants with evidence of underlying diseases were excluded. Concentrations of most plasma amino acids increased with gestational and maturational age; urinary excretion followed an opposite course. Few amino acids depended on postnatal age. Plasma amino acids did not correlate inversely to their counterparts in urine indicating that plasma amino acids do not simply reflect kidney function. Some amino acids in blood and urine were linked to nutrient intake and body weight. Our data clearly indicate the heterogeneity of the preterm cohort; therefore, gestational age-matched reference values have to be used for diagnostic purposes in preterm infants.

Publication types

  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Aging
  • Amino Acid Metabolism, Inborn Errors / diagnosis
  • Amino Acids / blood*
  • Amino Acids / urine*
  • Birth Weight
  • Body Weight
  • Child Development
  • Cohort Studies
  • Diet
  • Early Diagnosis
  • Enteral Nutrition*
  • Female
  • Food, Fortified
  • Gestational Age
  • Humans
  • Infant
  • Infant Formula
  • Infant, Newborn
  • Infant, Premature / blood*
  • Infant, Premature / urine*
  • Male
  • Milk, Human
  • Reference Values
  • Sex Characteristics


  • Amino Acids