title: Rapid assessment of renal reserve in young adults by cystatin C.
abstract: BACKGROUND
  The kidney can increase glomerular filtration rate (GFR) in response to a protein load (renal reserve). In a pilot study of healthy young adults we examined renal reserve using changes in serum cystatin C (cysC).
  
  
  METHODS
  Glomerular filtration rate was obtained using iohexol single slope plasma disappearance. To stimulate GFR, subjects ingested a beefburger containing 60 grams of protein. CysC was measured by immunonephelometry before and 125-141 minutes after protein loading.
  
  
  RESULTS
  All subjects were found to have a normal iohexol plasma disappearance GFR with a mean of 104.6 ± 9.9 mL/min per 1.73 m(2). CysC decreased in each subject after the meat meal. Baseline cysC-based estimated GFR was 98.1 ± 9.1 mL/min per 1.73 m(2) with a mean increase of 12.0 ± 5.2 (p = 0.0003).
  
  
  CONCLUSIONS
  Our study showed a consistent decrease in serum cysC and increase in cysC-based estimated GFR following a protein load in young adults. Further studies are needed using renal clearance methods to confirm that cysC accurately determines renal reserve in patients with and without chronic kidney disease.
authors: a Pediatric Nephrology, University of Rochester Medical Center , Rochester, NY USA.
authors: Dana Y
authors: DY
authors: Fuhrman
authors: a Pediatric Nephrology, University of Rochester Medical Center , Rochester, NY USA.
authors: Paula S
authors: PS
authors: Maier
authors: a Pediatric Nephrology, University of Rochester Medical Center , Rochester, NY USA.
authors: George J
authors: GJ
authors: Schwartz
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007472:Iohexol / Q000493:pharmacokinetics; D007668:Kidney / Q000502:physiology*; D008297:Male; D010865:Pilot Projects; D012016:Reference Values; D055815:Young Adult
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D004044:Dietary Proteins; D007472:Iohexol
keywords: Chronic kidney disease; clearance; creatinine; cystatin C; estimated GFR; glomerular filtration rate