title: Phosphorus metabolism in peritoneal dialysis- and haemodialysis-treated patients.
abstract: Phosphorus control is generally considered to be better in peritoneal dialysis (PD) patients as compared with haemodialysis (HD) patients. Predialysis phosphorus concentrations are misleading as a measure of phosphorus exposure in HD, as these neglect significant dialysis-related fluctuations.
  
  
  
  Parameters of mineral metabolism, including parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF-23), were determined in 79 HD and 61 PD patients. In PD, phosphorus levels were determined mid-morning. In HD, time-averaged phosphorus concentrations were modelled from measurements before and after the mid-week dialysis session. Weekly renal, dialytic and total phosphorus clearances as well as total mass removal were calculated from urine and dialysate collections.
  
  
  
  Time-averaged serum phosphorus concentrations in HD (3.5 ± 1.0 mg/dL) were significantly lower than the mid-morning concentrations in PD (5.0 ± 1.4 mg/dL, P < 0.0001). In contrast, predialysis phosphorus concentrations (4.6 ± 1.4 mg/dL) were not different from PD. PTH and FGF-23 levels were significantly higher in PD. Despite higher residual renal function, total phosphorus clearance was significantly lower in PD (P < 0.0001). Total phosphorus mass removal, conversely, was significantly higher in PD (P < 0.05).
  
  
  
  Our data suggest that the time-averaged phosphorus concentrations in patients treated with PD are higher as compared with patients treated with HD. Despite a better preserved renal function, total phosphorus clearance is lower in patients treated with PD. Additional studies are needed to confirm these findings in a population with a different demographic profile and dietary background and to define clinical implications.
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Björn K I
authors.initials: BK
authors.lastname: Meijers
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Bert
authors.initials: B
authors.lastname: Bammens
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Viaene
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Claes
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Ben
authors.initials: B
authors.lastname: Sprangers
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Naesens
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Tiny
authors.initials: T
authors.lastname: Hoekstra
authors.affiliation: Nephrology and Clinical Immunology, Uniklinik RWTH Aachen, Aachen, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Schlieper
authors.affiliation: Department of Endocrinology, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Vanderschueren
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, B-3000 Leuven, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Kuypers
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D015314:Dialysis Solutions; D005260:Female; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010530:Peritoneal Dialysis; D010758:Phosphorus / Q000097:blood*; D006435:Renal Dialysis
chemical_list: D015415:Biomarkers; D015314:Dialysis Solutions; C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D010758:Phosphorus; D000089703:Fibroblast Growth Factor-23
keywords: CKD-MBD; FGF-23; dialysis; hyperphosphataemia; mineral metabolism