Dynamic behavior of plasma phosphate in chronic dialysis patients.

1. Change in the plasma P concentration during intra- and interdialytic phases is notably different from that for BUN, CR and UA. Reduction rate for P depends on its pretreatment concentration. Plasma P is apt to level off or rebound even during a treatment and quickly returns to the pretreatment level after it is terminated. 2. In short-term evaluations, occurrence of P rebound during a treatment does not correlate with factors such as meal, A1 gel, dialyzer type, dialyzer membrane and therapeutic mode, but with the pretreatment P concentration. Once it reaches a threshold level inherent to each patient, plasma P seems to rebound. 3. Pretreatment P concentration in each patient seemed to be controlled in a relatively narrow range. 4. While apparent generation rates (G) estimated with a single compartmental kinetic model are stable during intra- and interdialytic phases as to BUN, CR and UA, G for P seems to be significantly enhanced especially during the latter period of the treatment and immediately after the termination of the treatment.