Our recent work proposed a pseudo one-compartment model for describing intradialysis and postdialysis rebound kinetics of
phosphorus. In this model,
phosphorus is removed directly from a central distribution volume with the rate of
phosphorus mobilization from a second, very large compartment proportional to the
phosphorus mobilization clearance. Here, we evaluated factors of
phosphorus mobilization clearance and postdialysis central distribution volume from 774 patients in the HEMO Study.
Phosphorus mobilization clearance and postdialysis central distribution volume were 87 (65, 116) ml/min, median (interquartile range), and 9.4 (7.2, 12.0) liter, respectively. The
phosphorus mobilization clearance was significantly higher for male patients than for female patients. Both the
phosphorus mobilization clearance and the postdialysis central distribution volume were significantly associated with postdialysis
body weight but negatively with the predialysis serum
phosphorus concentration. The postdialysis central distribution volume was also significantly associated with age. Overall, the postdialysis central distribution volume was 13.6% of the postdialysis
body weight. Thus, the
phosphorus mobilization clearance during
hemodialysis is higher when predialysis serum
phosphorus concentration is low and higher in male patients than in female patients. The central distribution volume of
phosphorus is a space approximating the extracellular fluid volume.