Selenium Metabolism in Patients on Continuous Ambulatory Peritoneal Dialysis

Selenium is an essential trace element for living organisms. In many publications, researchers express concern about a possible Se deficiency in patients with end-stage chronic renal failure (ESCRF) undergoing continuous ambulatory peritoneal dialysis (CAPD). However, in a number of published articles, the data provide no evidence that patients under CAPD develop Se deficiency.We investigated Se metabolism in ESCRF patients on CAPD.The study was carried out at the Department of Propaedeutic Surgery, Athens University; the Laboratory for Material Analysis of the Nuclear Physics Institute; and the State General Hospital, Athens, Greece.The study group included 24 patients on CAPD treatment, 14 ESCRF patients, and 17 healthy controls. We measured the Se and Fe content of serum, blood, and erythrocytes. We also measured hematocrit, serum total proteins and albumins, and Se in dialysate effluent.As compared with healthy subjects, the ESCRF and CAPD patients exhibited reduced serum concentrations of Se. However, considering the difference in hematocrit values, the total serum-transported Se per liter of blood was close to normal. Erythrocyte Se proved normal for both groups. The measured Se in the spent effluent indicates that patients under CAPD receive approximately 100 microg Se from their daily diet, as normal subjects do. The Se measurement data from the effluent indicate that 90% of the Se carried by the serum is bound to albumins and that only the remaining 10% is in the form of low molecular weight selenate, free to pass the peritoneal membrane. Of the 24 CAPD patients studied, 4 patients (all women) showed extremely low Se serum levels. Data suggest that those low levels are more likely due to the significantly lower serum albumin levels in the 4 patients than to an insufficient dietary intake.Data from the present experimental work suggest that patients undergoing CAPD receive the necessary quantities of Se from their regular diet. The data contradict statements in the relevant literature that CAPD patients develop Se deficiency.