title: Serum cystatin C is a more sensitive and more accurate marker of glomerular filtration rate than enzymatic measurements of creatinine in renal transplantation.
abstract: OBJECTIVE
  Serum creatinine has several drawbacks as marker of glomerular filtration rate (GFR), and therefore serum cystatin C has been proposed as a more optimal GFR marker. Previous reports have suggested benefits of serum cystatin C measurements in patients with renal transplants. The purpose of the present study was to evaluate the diagnostic accuracy of cystatin C measurements compared with enzymatic creatinine measurements as serum markers of GFR (established from plasma clearance of iohexol) in a large cohort of stable renal transplant recipients and in the early postoperative phase.
  
  
  METHODS
  Renal transplant patients (n = 125) with stable graft function were evaluated from reciprocals of serum creatinine and cystatin C compared with iohexol clearance. Fourteen patients were examined immediately after the onset of renal function. Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method.
  
  
  RESULTS
  In stable renal transplant recipients, serum cystatin C showed a significantly (p = 0.033) closer correlation (r = 0.89 or 79% co-variance) with iohexol clearance than did serum creatinine (r = 0.81 or 66% co-variance). Using the chi(2) test and a cut-off at 60 ml/min/1.73 m(2), serum cystatin C levels demonstrated significantly higher sensitivity for early GFR impairment (p = 0.0045) compared with serum creatinine measurements. On the first day after transplantation, serum cystatin C fell more rapidly than serum creatinine.
  
  
  CONCLUSIONS
  Serum cystatin C levels correlate significantly closer to accurate measurements of GFR and are significantly more sensitive to detect early GFR impairment than enzymatic measurements of creatinine in serum.
authors.affiliation: Department of Nephrology and Transplantation, Malmö University Hospital, Malmö, Sweden. Anders.Christensson@medforsk.mas.lu.se
authors.forename: Anders
authors.initials: A
authors.lastname: Christensson
authors.forename: Jana
authors.initials: J
authors.lastname: Ekberg
authors.forename: Anders
authors.initials: A
authors.lastname: Grubb
authors.forename: Henrik
authors.initials: H
authors.lastname: Ekberg
authors.forename: Veronica
authors.initials: V
authors.lastname: Lindström
authors.forename: Hans
authors.initials: H
authors.lastname: Lilja
mesh_terms: D000328:Adult; D000368:Aged; D000581:Amidohydrolases / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007472:Iohexol / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000628:therapy; D007678:Kidney Glomerulus / Q000201:enzymology*; D016030:Kidney Transplantation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007472:Iohexol; D003404:Creatinine; D000581:Amidohydrolases; C019946:creatininase