Steady state phosphorus mass balance model during hemodialysis based on a pseudo one-compartment kinetic model.
OBJECTIVE
Mathematical models of phosphorus kinetics and mass balance during hemodialysis are in early development. We describe a theoretical phosphorus steady state mass balance model during hemodialysis based on a novel pseudo one-compartment kinetic model.


METHODS
The steady state mass balance model accounted for net intestinal absorption of phosphorus and phosphorus removal by both dialysis and residual kidney function. Analytical mathematical solutions were derived to describe time-dependent intradialytic and interdialytic serum phosphorus concentrations assuming hemodialysis treatments were performed symmetrically throughout a week.


RESULTS
Results from the steady state phosphorus mass balance model are described for thrice weekly hemodialysis treatment prescriptions only. The analysis predicts 1) a minimal impact of dialyzer phosphorus clearance on predialysis serum phosphorus concentration using modern, conventional hemodialysis technology, 2) variability in the postdialysis-to-predialysis phosphorus concentration ratio due to differences in patient-specific phosphorus mobilization, and 3) the importance of treatment time in determining the predialysis serum phosphorus concentration.


CONCLUSIONS
We conclude that a steady state phosphorus mass balance model can be developed based on a pseudo one-compartment kinetic model and that predictions from this model are consistent with previous clinical observations. The predictions from this mass balance model are theoretical and hypothesis-generating only; additional prospective clinical studies will be required for model confirmation.
Medical Products R&D-Renal, Baxter Healthcare Corporation, McGaw Park, IL, USA. ken_leypoldt@baxter.com
John K
JK
Leypoldt
Baris U
BU
Agar
Alp
A
Akonur
Mary E
ME
Gellens
Bruce F
BF
Culleton
D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy*; D008657:Metabolic Clearance Rate / Q000502:physiology; D008954:Models, Biological; D010758:Phosphorus / Q000493:pharmacokinetics*; D006435:Renal Dialysis; D013997:Time Factors
D010758:Phosphorus