PARENTERAL SELENIUM SUPPLEMENTATION IN CRITICALLY ILL PATIENTS - EFFECTS ON ANTIOXIDANT METABOLISM

Decreased plasma selenium (Se) levels are common in critically ill pat ients. Oxidative stress is regarded as one possible cause of the Se de ficiency. We investigated in 20 critically ill patients with decreased plasma selenium concentrations the antioxidant metabolism during pare nteral selenium supplementation (week 1: 2 x 500 mu g; week 2: 1 x 500 mu g, week 3: 3 x 100 mu g sodium selenite). As marker of oxidative s tress we measured the plasma malondialdehyde levels on days 0, 1, 3, 7 , 14, and 21. The content of reduced and oxidized glutathione as well as the leucocyte activity marker elastase were estimated on the same d ays. Initial plasma Se levels were considerably decreased (0.44 +/- 0. 1 mu mol/l, mean +/- SEM). After one day of supplementation Se concent rations were in the reference range. Plasma malondialdehyde levels and the ratio of oxidized and reduced glutathione were initially elevated and decreased beginning on day 3 of supplementation. The mean elastas e level was 113 +/- 10 mu g/l on day 0. On day 3 elastase values decre ased significantly (85 +/- 13 mu g/l, p < 0.05; day 21, 19 +/- 7 mu g/ l, p < 0.001). Antioxidant metabolism showed significant changes begin ning after 72 hours of therapy. This latency may be explained with the induction of the enzyme glutathione peroxidase. The lowered plasma Se concentrations measured in the critically ill patients and the signif icant effects on antioxidant metabolism during supplementation emphasi zed the importance of selenium administration in these patients.