Copper, selenium, zinc, and thiamine balances during continuous venovenous hemodiafiltration in critically ill patients1–3

Background: Acute renal failure is a serious complication in crit-ically ill patients and frequently requires renal replacement therapy, which alters trace element and vitamin metabolism. Objective: The objective was to study trace element balances during continuous renal replacement therapy (CRRT) in intensive care pa-tients. Design: In a prospective randomized crossover trial, patients with acute renal failure received CRRT with either sodium bicarbonate (Bic) or sodium lactate (Lac) as a buffering agent over 2 consecutive 24-h periods. Copper, selenium, zinc, and thiamine were measured with highly sensitive analytic methods in plasma, replacement so-lutions, and effluent during 8-h periods. Balances were calculated as the difference between fluids administered and effluent losses and were compared with the recommended intakes (RI) from parenteral nutrition. Results: Nineteen sessions were conducted in 11 patients aged 65 10 y. Baseline plasma concentrations of copper were normal, whereas those of selenium and zinc were below reference ranges; glutathione peroxidase was in the lower range of normal. The re-placement solutions contained no detectable copper, 0.01mol Se/L (Bic and Lac), and 1.42 (Bic) and 0.85 (Lac) mol Zn/L. Micronu-trients were detectable in all effluents, and losses were stable in each patient; no significant differences were found between the Bic and Lac groups. The 24-h balances were negative for selenium (0.97 mol, or 2 times the daily RI), copper (6.54mol, or 0.3 times the daily RI), and thiamine (4.12 mg, or 1.5 times the RI) and modestly positive for zinc (20.7 mol, or 0.2 times the RI). Conclusions: CRRT results in significant losses and negative bal-ances of selenium, copper, and thiamine, which contribute to low plasma concentrations. Prolonged CRRT is likely to result in sele-nium and thiamine depletion despite supplementation at recom-mended amounts. Am J Clin Nutr 2004;80:410–6