title: Prediction of glomerular filtration rate in renal transplant recipients: cystatin C or modification of diet in renal disease equation?
abstract: BACKGROUND
  To overcome disadvantages of serum creatinine two strategies have been suggested to identify patients with reduced glomerular filtration rate (GFR). On the one hand, the Modification of Diet in Renal Disease (MDRD) equation is now recommended to classify the stage of chronic kidney disease. On the other hand, cystatin C (Cys C) has been investigated in numerous studies, finding a higher sensitivity than creatinine in detecting diminished GFR. To date, no comparison of both strategies in patients after renal transplantation has been performed.
  
  
  METHODS
  One hundred and five consecutive renal transplant recipients underwent (99m)Tc-DTPA-- clearance measurement. Simultaneously, MDRD estimates were calculated and Cys C serum levels were determined. ROC analyses were performed at different decision points from 20 to 70 mL/min/1.73 m(2).
  
  
  RESULTS
  Although the area under the curve did not differ significantly between MDRD and Cys C within the tested GFR range, the AUC for Cys C tended to be higher when GFR exceeded 55 mL/min/1.73 m(2). A significantly higher diagnostic accuracy for Cys C compared with MDRD (p = 0.045 at 65 mL/min/1.73 m(2)) was found when investigating the subgroup of patients with well-functioning grafts (GFR>40 mL/min/1.73 m(2)).
  
  
  CONCLUSIONS
  MDRD equation is equivalent to Cys C measurement in renal transplant recipients. As availability of MDRD is superior to Cys C, we recommend GFR estimation using the MDRD equation. Nevertheless, Cys C may serve as a confirmation test of high MDRD estimates in patients with well-functioning grafts because of superior accuracy in these patients.
authors.affiliation: Department of Internal Medicine I, University of Bonn, Bonn, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Pöge
authors.forename: Thomas
authors.initials: T
authors.lastname: Gerhardt
authors.forename: Birgit
authors.initials: B
authors.lastname: Stoffel-Wagner
authors.forename: Holger
authors.initials: H
authors.lastname: Palmedo
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Klehr
authors.forename: Tilman
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: Rainer P
authors.initials: RP
authors.lastname: Woitas
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007166:Immunosuppressive Agents; D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate