Double Isotope Measurement of Peritoneal Clearance of Iodide and Albumin Loss during Peritoneal Dialysis in Man

131I-labelled Human Serum Albumin and 125I-sodium iodide were used to measure protein loss from the peritoneum and peritoneal clearance of iodide in a group of 8 uraemic patients, each one being studied after a different number of dialyses. Both albumin loss and iodide clearance reached a maximum at about the 10th dialytic treatment and then tended towards the initial levels. Protein loss as determined isotopically was markedly lower than indicated by direct radioimmunoassay measurements performed in three cases. Fitting experimental points by a model which assumes direct passage of protein from plasma to peritoneal cavity suggests the presence of a "delay" pool between plasma and the peritoneal cavity itself (extravascular sites adjacent to peritoneum?). The shorter retention time of the dialysis solution in the abdomen (4-8 minutes) seemed to us to cause lower protein losses than reported by authors using longer retention times.