[Modelling of phosphorus transfers during haemodialysis]

Chronic kidney disease causes hyperphosphatemia, which is associated with increased cardiovascular risk and mortality. In patients with end-stage renal disease, haemodialysis allows the control of hyperphosphatemia. During a 4-h haemodialysis session, between 600 and 700mg of phosphate are extracted from the plasma, whereas the latter contains only 90mg of inorganic phosphate. The precise origin of phosphates remains unknown. The modelling of phosphorus transfers allows to predict the outcome after changes in dialysis prescription (duration, frequency) with simple two-compartment models and to describe the transfers between the different body compartments with more complex models. Work using ³¹P nuclear magnetic resonance spectroscopy performed in animals showed an increase in intracellular phosphate concentration and a decrease in intracellular ATP during a haemodialysis session suggesting an intracellular origin of phosphates.