Patient-specific phosphorus (P) mobilization clearance during hemodialysis (HD): Dependence on body weight and predialysis plasma P concentration

We have recently demonstrated that a pseudo one-compartment kinetic model that includes phosphorus (P) mobilization from other body compartments into extracellular fluids, can be used to describe intradialytic and postdialytic rebound kinetics of P during conventional hemodialyis (HD), chronic hemodialyis (CHD) as well as short, 2-hour HD treatments or standard hemodialyis (SHD).
In this study we determined patient-specific P mobilization clearances (K _M) during in-center nocturnal hemodialysis (ICNHD) and short daily hemodialysis with low dialyzer P clearance (SDHD-L).

Dialyzer P clearances were 134 plus/minus 20 (mean SD) ml/min and 95 plus/minus 11 ml/min for ICNHD and SDHD-L, respectively. Estimated K _M values for the respective therapies were 124 plus/minus 83 ml/min and 103 plus/minus 33 ml/min, comparable to those determined previously during CHD and SHD of 98 plus/minus 44 ml/min (N= 21). When the data from all HD therapies were combined, K _M was found to be directly correlated with postdialysis body weight (r= 0.38, P= 0.025) and inversely correlated with predialysis P concentration (r= -0.47, P= 0.0046).
These findings extend the types of HD therapies where a pseudo one-compartment model can be used to assess P kinetics. Association of K _M with postdialysis body weight and predialysis P concentration suggests that K _M has the typical body size characteristics of an intercompartmental clearance and that higher predialysis P concentrations may result in hindered P mobilization.

BU Agar, A Akonur and JK Leypoldt are paid are employees of Baxter Healthcare.