title: Assessment of glomerular filtration rate in the neonate: is creatinine the best tool?
abstract: OBJECTIVE
  This article answers the question of whether creatinine is the best biomarker for monitoring neonatal glomerular filtration rate (GFR) in view of recent advances in measuring neonatal renal function.
  
  
  RESULTS
  We rely largely on serum creatinine for the estimation of GFR in the newborn, even though creatinine is freely exchanged through the placenta. During the first few days of life, the serum creatinine reflects maternal renal function or the maternal creatinine. Back filtration of creatinine in preterm newborns is also a serious limitation. This review summarizes current knowledge on the prenatal and postnatal handling of creatinine as well as that of other, more novel biomarkers of GFR, such as cystatin C (CysC) and β-trace protein (BTP). Only small amounts of CysC cross the placenta, whereas BTP does not cross the placenta at all. However, BTP measurements are not widely available. Recent studies on renal volumetry are also discussed.
  
  
  CONCLUSIONS
  Currently, CysC may be the most suitable marker of neonatal renal function, but its availability is still limited, it is more costly, and the best method of reporting acute kidney injury and neonatal estimated GFR remains to be established.
authors.affiliation: aDepartment of Pediatrics bDepartment of Pathology and Laboratory Medicine cDepartment of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada dUniversidad Nacional Autónoma de México eDepartment of Neonatology, Hospital Angeles de Interlomas fLaboratorio de Investigacion en Nefrologia, Hospital Infantil de México Federico Gómez, México City, México.
authors.forename: Guido
authors.initials: G
authors.lastname: Filler
authors.forename: Ricardo
authors.initials: R
authors.lastname: Guerrero-Kanan
authors.forename: Ana Catalina
authors.initials: AC
authors.lastname: Alvarez-Elías
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn / Q000502:physiology*; D007234:Infant, Premature; D007668:Kidney / Q000196:embryology / Q000502:physiology; D038081:Organogenesis / Q000502:physiology
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine