title: C-terminal agrin fragment (CAF) as a serum biomarker for residual renal function in peritoneal dialysis patients.
abstract: BACKGROUND
  C-terminal agrin fragment (CAF, size 22 kDa) is a promising new biomarker for kidney function. This study evaluated the usefulness of CAF as a serum biomarker for residual renal function (RRF) in patients undergoing automated peritoneal dialysis (APD).
  
  
  METHODS
  Serum, urine and dialysate samples were obtained in 12 end-stage renal disease patients undergoing APD. Total, renal and peritoneal clearances were calculated for CAF, creatinine, blood urea nitrogen (BUN) and cystatin c. kt/V was computed, and RRF (in ml/min) was calculated as the arithmetic mean of creatinine and BUN clearance. Correlations between the biomarkers' serum concentrations, clearances, kt/V and RRF were computed.
  
  
  RESULTS
  Serum CAF concentrations were highly correlated with serum concentrations of creatinine (r = 0.806, p = 0.002), BUN (r = 0.727, p = 0.007), cystatin c (r = 0.839, p = 0.001) and inversely to 24-h urinary output (r = -0.669, p = 0.017). RRF was inversely correlated with serum concentrations of CAF, cystatin c and creatinine being highest for CAF (r = -0.734, p = 0.007) followed by cystatin c (r = -0.65, p = 0.022) and creatinine (r = -0.606, p = 0.037). Serum BUN was not significantly associated with RRF (r = -0.497, p = 0.101). Age, weight and gender did not significantly affect serum CAF concentrations.
  
  
  CONCLUSIONS
  Serum CAF provides a robust serum biomarker for RRF in peritoneal dialysis patients undergoing APD, possibly outperforming the value of conventional biomarkers.
authors.affiliation: Abteilung für Nephrologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany, dominik.steubl@gmx.de.
authors.forename: Dominik
authors.initials: D
authors.lastname: Steubl
authors.forename: Stefan
authors.initials: S
authors.lastname: Hettwer
authors.forename: Pius
authors.initials: P
authors.lastname: Dahinden
authors.forename: Peter
authors.initials: P
authors.lastname: Luppa
authors.forename: Ina-Christine
authors.initials: IC
authors.lastname: Rondak
authors.forename: Claudia
authors.initials: C
authors.lastname: Regenbogen
authors.forename: Konrad F
authors.initials: KF
authors.lastname: Stock
authors.forename: Lutz
authors.initials: L
authors.lastname: Renders
authors.forename: Uwe
authors.initials: U
authors.lastname: Heemann
authors.forename: Marcel
authors.initials: M
authors.lastname: Roos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018171:Agrin / Q000097:blood* / Q000652:urine; D015415:Biomarkers / Q000097:blood; D001806:Blood Urea Nitrogen; D003404:Creatinine / Q000097:blood* / Q000652:urine; D055316:Cystatin C / Q000097:blood* / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood* / Q000652:urine; D010530:Peritoneal Dialysis; D010865:Pilot Projects; D011446:Prospective Studies
chemical_list: D018171:Agrin; D015415:Biomarkers; C000602450:C-terminal agrin fragment; D055316:Cystatin C; D010446:Peptide Fragments; D003404:Creatinine