title: Cystatin C-calculated Glomerular Filtration Rate-A Marker of Early Renal Dysfunction in Patients With Neuropathic Bladder.
abstract: OBJECTIVE
  To asses if cystatin c-calculated glomerular filtration rate (GFR) can reveal chronic kidney disease (CKD) not detected by creatinine-based calculations in a larger prospective cohort of children with myelomeningocele (MMC). Wheelchair-bound MMC patients frequently have low muscle mass, and assessing renal deterioration based on creatinine-based GFR is imprecise. MMC patients are also at risk for end-stage renal disease.
  
  
  METHODS
  Prospectively enrolled patients with MMC underwent annual serum creatinine and cystatin c testing. Anthropometric measurements were obtained from clinic visit. The modified (bedside) Schwartz formula for creatinine-based GFR and the Zappitelli cystatin C formula were utilized for calculation. The exclusion criteria were patients with reduced GFR (CKD stage 2) or chronic CKD (CKD stage 3 and greater); these patients were excluded from analysis on the premise that they had already been identified for closer renal monitoring.
  
  
  RESULTS
  A total of 131 patients were included in the analysis. The median creatinine-based estimated GFR was 126.5 mL/min/1.73 m2(range: 22-310). The median cystatin C-based estimated rate was 98.5 mL/min/1.73 m2(range: 16-171), yielding an absolute median rate reduction of 30.2%. Using cystatin c-calculated GFR, CKD stage was upgraded from stage 1 to ≥2 in 34 patients (26%).
  
  
  CONCLUSIONS
  In MMC patients with poor muscle mass, cystatin C-based GFR is more sensitive than creatinine-based GFR in detecting early CKD. In this high-risk population, serial cystatin C estimation is a valuable tool in identifying children who may benefit from early nephrology referral and intervention.
authors.affiliation: Division of Pediatric Urology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA. Electronic address: pankajdangle@gmail.com.
authors.forename: Pankaj P
authors.initials: PP
authors.lastname: Dangle
authors.affiliation: Division of Pediatric Urology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Omar
authors.initials: O
authors.lastname: Ayyash
authors.affiliation: Division of Pediatric Urology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Audry
authors.initials: A
authors.lastname: Kang
authors.affiliation: Department of Pediatric Nephrology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Carlton
authors.initials: C
authors.lastname: Bates
authors.affiliation: Naval Medical Center Portsmouth, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Janelle
authors.initials: J
authors.lastname: Fox
authors.affiliation: Division of Pediatric Urology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Stephany
authors.affiliation: Division of Pediatric Urology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Cannon
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008591:Meningomyelocele / Q000097:blood / Q000150:complications*; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D012307:Risk Factors; D012680:Sensitivity and Specificity; D001750:Urinary Bladder, Neurogenic / Q000097:blood* / Q000150:complications
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine