title: Serum cystatin C during 30 postnatal days is dependent on the postconceptional age in neonates.
abstract: BACKGROUND
  Cystatin C (CysC) is a promising endogenous marker for renal function. However, the reference serum CysC level is not sufficiently studied in neonates. This study was conducted to investigate the reference level of serum CysC for neonates, including very low birth weight infants according to the postconceptional age (PCA).
  
  
  METHODS
  Serum CysC levels were measured in 883 blood samples (246 neonates including 127 premature infants). Infants with symptoms or signs of acute kidney injury, systemic illness, congenital anomaly, or renal pathology were excluded. CysC levels were analyzed for association between subgroups dichotomized by postnatal age and PCA.
  
  
  RESULTS
  Reference ranges of serum CysC were determined and a decreasing trend of CysC levels was observed as PCA increased, except for the first 3 postnatal days. CysC levels were negatively correlated with gestational age at birth, and PCA (P < 0.001), while positively correlated with postnatal age and serum creatinine (P < 0.001).
  
  
  CONCLUSIONS
  The reference level of serum CysC was determined according to postnatal age and PCA. As the reference CysC level was dependent on gestational age and PCA, consideration of these parameters is warranted when assessing CysC levels in neonates.
authors: Department of Pediatrics, School of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors: Ji-Hyun
authors: JH
authors: Lee
authors: Won-Ho
authors: WH
authors: Hahn
authors: Jaeouk
authors: J
authors: Ahn
authors: Ji-Young
authors: JY
authors: Chang
authors: Chong-Woo
authors: CW
authors: Bae
mesh_terms: D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000097:blood; D007677:Kidney Function Tests / Q000592:standards; D008297:Male; D011237:Predictive Value of Tests; D012016:Reference Values
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D003404:Creatinine