High-dose cysteine administration does not increase synthesis of the antioxidant glutathione preterm infants.
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.
te Braake
Frans W J
FW
Department of Pediatrics, Division of Neonatology, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, Netherlands.
Schierbeek
Henk
H
Vermes
Andras
A
Huijmans
Jan G M
JG
van Goudoever
Johannes B
JB
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
D000596:Amino Acids; D000975:Antioxidants; D003553:Cystine; D005978:Glutathione; D003545:Cysteine