title: Longitudinal study of Cystatin C in healthy term newborns.
abstract: OBJECTIVE
  The purpose of this study was to determine the levels of Cystatin C in healthy term newborns in the first month of life.
  
  
  BACKGROUND
  Cystatin C may be a suitable marker for determining the glomerular filtration rate because it is not affected by maternal renal function.
  
  
  METHODS
  Cohort study. Inclusion: term newborns with appropriate weight; mother without renal failure or drugs that could affect fetal glomerular filtration rate. Exclusion: malformations; hypertension or any condition that could affect glomerular filtration rate. Cystatin C (mg/L)and creatinine (rng/dl) were determined in the mother (Mo) and in the newborn at birth (Day-0), 3rd (Day-3), 7th(Day-7) and 28t>h(Day-28) days.
  
  
  METHODS
  one way ANOVA and Pearson's correlation tests. Sample size of 20 subjects for a = 5% and a power test = 80% (p<0.05).
  
  
  RESULTS
  Data from 21 newborns were obtained (mean + standard deviation): MoCystatin C=1.00 ± 0.20; Day-0 Cystatin C 1.70 ± 0.26; Day-3 Cystatin C = 1.51 ± 0.20; Day-7 Cystatin C = 1.54 ± 0.10; Day-28 Cystatin C = 1.51 ± 0.10. MoCystatin C was smaller than Day-0 Cystatin C (p < 0.001), while MoCreatinine was not different from Day-0 Creatinine. Cystatin C only decreased from Day-0 to Day-3 (p = 0.004) but newborns Creatinine decreased along the time. Correlations were obtained between MoCystatin C and MoCreatinine (p = 0.012), as well as Day-3 (p = 0.047) and Day-28 (p = 0.022) Cystatin C and Creatinine values.
  
  
  CONCLUSIONS
  Neonatal Cystatin C values were not affected by MoCystatin C and became stable from the 3rd day of life.
authors.affiliation: Department of Pediatrics, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Ana Carolina de Albuquerque Cavalcanti Ferreira
authors.initials: AC
authors.lastname: Novo
authors.forename: Lilian Dos Santos Rodrigues
authors.initials: Ldos S
authors.lastname: Sadeck
authors.forename: Thelma Suely
authors.initials: TS
authors.lastname: Okay
authors.forename: Clea Rodrigues
authors.initials: CR
authors.lastname: Leone
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D004812:Epidemiologic Methods; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009035:Mothers / Q000706:statistics & numerical data
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine