title: High-dose cysteine administration does not increase synthesis of the antioxidant glutathione preterm infants.
abstract: OBJECTIVE
  Our aim was to evaluate whether administration of additional cysteine is safe and stimulates glutathione synthesis in preterm infants in early life.
  
  
  METHODS
  We conducted a prospective, randomized, clinical trial with infants with birth weights of <1500 g (N = 20). The infants were assigned randomly to receive either a standard dose (45 mg/kg per day) or a high dose (81 mg/kg per day) of cysteine. Intakes of other amino acids were similar, providing a total protein intake of 2.4 g/kg per day in both groups. We recorded base requirements in the first 6 days of life. On postnatal day 2, we conducted a stable isotope study to determine glutathione concentrations and synthesis rates in erythrocytes.
  
  
  RESULTS
  Base requirements were higher in the high-dose cysteine group on days 3, 4, and 5. Despite an 80% increase in cysteine intake, plasma cystine concentrations did not increase. Glutathione concentrations and synthesis rates did not increase with additional cysteine administration.
  
  
  CONCLUSIONS
  Administration of a high dose of cysteine (81 mg/kg per day) to preterm infants seems clinically safe but does not stimulate glutathione synthesis, compared with a lower dose (45 mg/kg per day). Further research is required to determine whether there is significant benefit associated with cysteine supplementation.
authors.affiliation: Department of Pediatrics, Division of Neonatology, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, Netherlands.
authors.forename: Frans W J
authors.initials: FW
authors.lastname: te Braake
authors.forename: Henk
authors.initials: H
authors.lastname: Schierbeek
authors.forename: Andras
authors.initials: A
authors.lastname: Vermes
authors.forename: Jan G M
authors.initials: JG
authors.lastname: Huijmans
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Goudoever
mesh_terms: D000596:Amino Acids / Q000097:blood; D000975:Antioxidants / Q000378:metabolism*; D003545:Cysteine / Q000008:administration & dosage*; D003553:Cystine / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000096:biosynthesis* / Q000097:blood; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D019102:Infant, Very Low Birth Weight; D007263:Infusions, Parenteral; D008297:Male
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D003553:Cystine; D005978:Glutathione; D003545:Cysteine