title: Impact of gestational age and birth weight on amikacin clearance on day 1 of life.
abstract: OBJECTIVE
  Intrauterine growth restriction (IUGR) and prematurity are associated with a low nephron endowment. It can therefore be expected that neonates who are born premature and/or after IUGR have a lower GFR. Measurement of GFR in neonates is difficult, but the clearance of amikacin has been proven to be a reliable marker. We hypothesized that amikacin clearance is lower after IUGR or premature birth as a marker of low nephron endowment.
  
  
  METHODS
  Amikacin clearance was retrospectively analyzed in 161 neonates who received amikacin within the first 24 h of life. Using the MW/Pharm computer program, a population one-compartment model was calculated. The mean population pharmacokinetic parameters were individualized for each patient according to the maximum a posteriori Bayesian fitting method and provided the amikacin clearance.
  
  
  RESULTS
  Our results show that birth weight z score and gestational age are correlated with the clearance of amikacin (partial correlation coefficient 0.159, P = 0.046, and 0.396, P < 0.001, respectively), after correction for other factors.
  
  
  CONCLUSIONS
  We conclude that renal clearance on the first day of life is lower in neonates with a lower gestational age and/or birth weight z score. This indicates that both prematurity and IUGR impair GFR on the first day of life.
authors.affiliation: Department of Pediatric Nephrology, 804, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. m.schreuder@cukz.umcn.nl
authors.forename: Michiel F
authors.initials: MF
authors.lastname: Schreuder
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Wilhelm
authors.forename: Arend
authors.initials: A
authors.lastname: Bökenkamp
authors.forename: Simone M H
authors.initials: SM
authors.lastname: Timmermans
authors.forename: Henriette A
authors.initials: HA
authors.lastname: Delemarre-van de Waal
authors.forename: Joanna A E
authors.initials: JA
authors.lastname: van Wijk
mesh_terms: D000583:Amikacin / Q000493:pharmacokinetics*; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D001724:Birth Weight; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism*; D005865:Gestational Age; D005919:Glomerular Filtration Rate; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D007668:Kidney / Q000002:abnormalities* / Q000378:metabolism; D007677:Kidney Function Tests / Q000379:methods* / Q000592:standards; D008297:Male; D009399:Nephrons / Q000002:abnormalities / Q000378:metabolism; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents; D000583:Amikacin