title: Phosphate Kinetics During Weekly Cycle of Hemodialysis Sessions: Application of Mathematical Modeling.
abstract: Both hyperphosphatemia and hypophosphatemia are associated with increased morbidity and mortality among patients on dialysis. The control of serum phosphate concentration is a considerable clinical problem. Our study aimed to improve understanding of phosphate kinetics in patients on dialysis using mathematical modeling. Three consecutive hemodialysis sessions with breaks of 2-2-3 days were monitored in 25 patients. Phosphate concentration was measured every hour and 45 min after the end of dialysis in blood serum and every 30 min in dialysate during each session. Volume of fluid compartments and body composition were assessed by bioimpedance. The pseudo one-compartment model was applied to describe the profile of phosphate in blood serum during intra- and interdialytic periods of 1-week cycle of three hemodialysis sessions. Model parameters, such as phosphate internal clearance (KM ) and the rate of phosphate mobilization (RM ), were correlated with the reduction of serum phosphate concentration during dialysis (Cpost /Cpre ) and with equivalent continuous clearance (ECC) for phosphate. KM correlated negatively with predialysis serum phosphate concentration. There was significant positive correlation between RM and age. Postdialysis volume of phosphate central compartment was lower than, but correlated to, extracellular water volume. Parameters of the pseudo one-compartment model, phosphate internal clearance, and the rate of phosphate inflow to the central compartment (the one accessible for dialysis) from other phosphate body reservoirs correlated with the indices of dialysis adequacy, such as reduction of serum phosphate and ECC. The pseudo one-compartment model can be successfully extended from a single hemodialysis to the standard weekly cycle of sessions and the model parameters strongly correlate with the adequacy parameters of dialytic removal of phosphate.
authors.affiliation: Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Debowska
authors.affiliation: Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Poleszczuk
authors.affiliation: Department of Physical Therapy and Rehabilitation, Medical University of Lublin, Lublin, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Wojcik-Zaluska
authors.affiliation: Department of Nephrology, Medical University of Lublin, Lublin, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Ksiazek
authors.affiliation: Department of Nephrology, Medical University of Lublin, Lublin, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zaluska
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001823:Body Composition; D017097:Electric Impedance; D005260:Female; D015312:Hemodialysis Solutions / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D006801:Humans; D054559:Hyperphosphatemia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D017674:Hypophosphatemia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010710:Phosphates / Q000097:blood*; D006435:Renal Dialysis / Q000009:adverse effects
chemical_list: D015415:Biomarkers; D015312:Hemodialysis Solutions; D010710:Phosphates
keywords: Hemodialysis; Mineral metabolism; Modeling; Phosphate kinetics