title: Deuterium equilibrium time in saliva of newborn infants.
abstract: There is an increasing interest about the use of stable isotopes for body composition analysis in pediatrics. To ensure the success of total body water analysis by the deuterium dilution method, it is fundamental to determine the equilibrium time (plateau) of deuterium in the body fluid studied.
  
  
  OBJECTIVE
  We report here the equilibration time of deuterium oxide in the saliva of newborns after oral intake of the isotope.
  
  
  METHODS
  Twenty healthy term newborn infants, 10 males and 10 females, were analyzed. Saliva was collected from each newborn before the oral administration of a 100 mg/kg dose of deuterium oxide (baseline sample) and then at 1-hour intervals for 5 hours after administration. Deuterium enrichment of saliva was determined by isotope ratio mass spectrometry according to the recommendations of the International Atomic Energy Agency.
  
  
  RESULTS
  The plateau time of deuterium in saliva occurred 3 hours after oral administration of the stable isotope.
  
  
  CONCLUSIONS
  These data are essential for further studies on the body composition of newborn infants. To the best of our knowledge, this is the first study regarding the equilibration time of deuterium in the saliva of term newborns.
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto,University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Luis Angelo Marti
authors.initials: LA
authors.lastname: Traver
authors.forename: Francisco Eulógio
authors.initials: FE
authors.lastname: Martinez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ferriolli
authors.forename: Júlio Sérgio
authors.initials: JS
authors.lastname: Marchini
authors.forename: Jacqueline Pontes
authors.initials: JP
authors.lastname: Monteiro
authors.forename: Karina
authors.initials: K
authors.lastname: Pfrimer
authors.forename: Ana Paula Michelin
authors.initials: AP
authors.lastname: Sanchez
authors.forename: Thais
authors.initials: T
authors.lastname: de Oliveira
authors.forename: Carlos
authors.initials: C
authors.lastname: Ducatti
authors.forename: José Simon
authors.initials: JS
authors.lastname: Camelo