title: Cystatin C and beta2-microglobulin: markers of glomerular filtration in critically ill children.
abstract: BACKGROUND
  Parameters allowing regular evaluation of renal function in a paediatric intensive care unit (PICU) are not optimal. The aim of the present study was to analyse the utility of serum cystatin C and beta2-microglobulin (B2M) in detecting decreased glomerular filtration rate in critically ill children.
  
  
  METHODS
  This was a prospective, observational study set in an eight-bed PICU. Twenty-five children were included. The inverses of serum creatinine, cystatin C, and B2M were correlated with creatinine clearance (CrC) using a 24-hour urine sample and CrC estimation by Schwartz formula (Schwartz). The diagnostic value of serum creatinine, cystatin C, and B2M to identify a glomerular filtration rate under 80 ml/minute per 1.73 m(2) was evaluated using receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  Mean age was 2.9 years (range, 0.1 to 13.9 years). CrC was less than 80 ml/minute per 1.73 m(2) in 14 children, and Schwartz was less than 80 ml/minute per 1.73 m(2) in 9 children. Correlations between inverse of B2M and CrC (r = 0.477) and between inverse of B2M and Schwartz (r = 0.697) were better than correlations between inverse of cystatin C and CrC (r = 0.390) or Schwartz (r = 0.586) and better than correlations between inverse of creatinine and CrC (r = 0.104) or Schwartz (r = 0.442). The ability of serum cystatin C and B2M to identify a CrC rate and a Schwartz CrC rate under 80 ml/minute per 1.73 m(2) was better than that of creatinine (areas under the ROC curve: 0.851 and 0.792 for cystatin C, 0.802 and 0.799 for B2M, and 0.633 and 0.625 for creatinine).
  
  
  CONCLUSIONS
  Serum cystatin C and B2M were confirmed as easy and useful markers, better than serum creatinine, to detect acute kidney injury in critically ill children.
authors.affiliation: Hospital Universitario Central de Asturias, University of Oviedo, Julian Claveria Street, 33006, Oviedo, Spain. josedahm@yahoo.es
authors.forename: José David
authors.initials: JD
authors.lastname: Herrero-Morín
authors.forename: Serafín
authors.initials: S
authors.lastname: Málaga
authors.forename: Nuria
authors.initials: N
authors.lastname: Fernández
authors.forename: Corsino
authors.initials: C
authors.lastname: Rey
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Diéguez
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Solís
authors.forename: Andrés
authors.initials: A
authors.lastname: Concha
authors.forename: Alberto
authors.initials: A
authors.lastname: Medina
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood / Q000652:urine; D016638:Critical Illness; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D051437:Renal Insufficiency / Q000097:blood* / Q000175:diagnosis* / Q000652:urine; D001613:beta 2-Microglobulin / Q000097:blood*
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D001613:beta 2-Microglobulin; D003404:Creatinine