TRANSPERITONEAL ABSORPTION AND KINETICS OF CHROMIUM IN THE CONTINUOUSAMBULATORY PERITONEAL-DIALYSIS PATIENT - AN EXPERIMENTAL AND MATHEMATICAL-ANALYSIS

The functional model of Cr kinetics and metabolism described by Lim et al. [Am J Physiol 1983;224:R445-R454] for healthy people was adapted to the specific situation of the continuous ambulatory peritoneal dial ysis (CAPD) patient. For this purpose 3 CAPD patients were submitted t o an acute Cr-51-labelled dialysis dwell of 6 h. The rate of uptake of Cr in the plasma appeared to be equal to its disappearance rate from the peritoneal fluid. The plasma levels increased to a constant value in the first 2 h after the start of the dialysis session. The amount o f Cr cumulatively excreted in the urine over the followup period of 10 -12 days was 10-15% of the amount absorbed during the acute dwell. The experimental pharmacokinetic data were in close agreement with the va lues predicted by the modified functional model for Cr(III) kinetics a nd metabolism. According to this model, the effect of long-term CAPD t reatment (10 years) should result in an accumulation of Cr with a fact or of 100 in those organs, especially liver and spleen, known to have a slow exchange of Cr with the central plasma compartment. This predic ted and dramatic increase was in close agreement with the Cr concentra tions found in liver tissue of 3 patients who died after a variable ti me on CAPD.