title: Serum creatinine concentration in very-low-birth-weight infants from birth to 34-36 wk postmenstrual age.
abstract: BACKGROUND
  Serum creatinine (s[Cr]) reference ranges for very-low-birth-weight (VLBW) infants must account for physiologic changes in the first months of life.
  
  
  METHODS
  We retrospectively identified a sample of 218 appropriate-for-gestational age (GA) VLBW infants without risk factors for renal impairment, and classified into one of three GA groups: 25-27, 28-29, and 30-33 wk. We observed three phases of s[Cr] change (initial, decline, and equilibrium), whose characteristics varied by GA group. We used mixed-effects regression models to estimate mean and upper 95th prediction interval of s[Cr] for each GA group from birth to 34-36 wk post menstrual age (PMA).
  
  
  RESULTS
  In phase I, s[Cr] increased after birth, then returned slowly to baseline. The duration of phase I and the magnitude of s[Cr] rise decreased with increasing GA. In phase II, s[Cr] declined abruptly at a rate that increased with GA. A gradual transition to phase III, a steady-state equilibrium with similar s[Cr] among GA groups, began at approximately 34-36 wk PMA. We constructed GA group-specific nomograms depicting s[Cr] behaviour across the three phases.
  
  
  CONCLUSIONS
  The reference ranges derived from a sample of infants without risk factors for renal impairment provide a context for quantitative interpretation of s[Cr] trends in VLBW infants.
authors: Department of Pediatrics, Columbia University Medical Center, New York, New York.
authors: David A
authors: DA
authors: Bateman
authors: Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota.
authors: William
authors: W
authors: Thomas
authors: Department of Pediatrics, Columbia University Medical Center, New York, New York.
authors: Elvira
authors: E
authors: Parravicini
authors: Department of Pediatrics, Columbia University Medical Center, New York, New York.
authors: Elena
authors: E
authors: Polesana
authors: Department of Pediatrics, University of Bologna, Bologna, Italy.
authors: Chiara
authors: C
authors: Locatelli
authors: Department of Pediatrics, Columbia University Medical Center, New York, New York.
authors: John M
authors: JM
authors: Lorenz
mesh_terms: D001724:Birth Weight; D001831:Body Temperature; D003404:Creatinine / Q000097:blood*; D004573:Electrolytes; D005260:Female; D005839:Gentamicins / Q000737:chemistry; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood; D019102:Infant, Very Low Birth Weight / Q000097:blood*; D008297:Male; D049451:Nomograms; D036801:Parturition; D012016:Reference Values; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
chemical_list: D004573:Electrolytes; D005839:Gentamicins; D003404:Creatinine