FP796THE ROLE OF DIALYSIS MEMBRANES ON INTRADIALYTIC SELENIUM EXCRETION AND SELENIUM STATUS IN CHRONIC HEMODIALYSIS PATIENTS

Abstract

Introduction and Aims: Dialysis membrane has been implicated in selenium deficiency in chronic hemodialysis(HD) patients. We investigated selenium excretion through different membranes during dialysis session and the role of intradialytic element loss on selenium status in HD. Methods: Forty one patients were studied, men/women=27/14, 67(25-85) years old, on chronic HD since 62(6-307) months. Group A included 19 patients on standard hemodialysis(SHD) with low flux polysulfone membrane, group B 10 patients on SHD with ethylenvinylalcool(EVAL) membrane and group C 12 patients on hemodiafiltration with polyamide/polyarylether sulfone/polyvinylpyrrolidone membrane. A control group D consisted of 16 age and gender-matched healthy subjects. Selenium was measured by atomic absorption spectrometry in blood before and after dialysis session, in affluent and effluent dialysate collected at the beginning, the end and every hour during session, in concentrated dialysate and in replacement solution used for hemodiafiltration. Results: In the total of patients, pre-dialysis serum selenium levels were lower than those in healthy controls (101,9±43,9 vs 129,9±46,2 μg/L-p=0,04) and post-dialysis serum selenium levels were marginally reduced (101,9±43,9 to 91,7±27,6 μg/L-p=0,05). Serum selenium levels decreased significantly at the session end only in hemodiafiltration (122,0±65,4 to 101,4±30,1 μg/L-p=0,04) and remained unchanged in SHD patients despite hemoconcentration, findings compatible with selenium loss during dialysis treatment. The excreted selenium mass into effluent dialysate was greater in hemodiafiltration compared to SHD patients (2975±1974 vs 1529±1088 μg-p=0,03), with significant difference only between C and A groups (2975±1974 vs 1407±1043 μg-p=0,04) and no difference between A and B groups. However, in hemodiafiltration patients pre-dialysis serum selenium levels were similar to those in healthy controls (122,0±65,4 μg/L vs 129,9±46,2-p=NS), and only group A and B patients had lower pre-dialysis serum selenium levels compared to healthy individuals (respectively 95,3±41,7 and 89,7±43,0 vs 129,9±46,2 μg/L-p=0,05 and p=0,03 respectively). No selenium was detected in concentrated and affluent dialysates and in hemodiafiltration replacement fluid. In the total of patients direct correlations of pre-dialysis serum selenium levels were found with serum urea (R=0,354-p=0,03), albumin (R=0,375-p=0,03) and magnesium levels (R=0,678-p<0,001) and a negative correlation with serum glucose levels (R=0,380-p=0,03). Conclusions: Selenium excretion in effluent dialysate was found with all three membrane types, but intradialytic loss could contribute to selenium deficiency only in SHD and strangely not in hemodiafiltration patients. Investigation of the role of additional factors, such as diabetes and nutritional status, would be interesting.