ObjectiveTo investigate plasma aluminum levels in critically ill patients requiring continuous venovenous hemofiltration (CVVH), while receiving sucralfate for stress ulcer prophylaxis.DesignRandomized, controlled study.SettingCardiothoracic intensive care unit.PatientsTwenty postoperative cardiac surgical patientsInterventionsTwenty patients requiring CVVH support for acute renal failure were randomized into two groups for concurrent stress ulcer prophylaxis. Group 1 (n = 10) received nasogastric sucralfate, and group 2 patients received intravenous ranitidine. Plasma aluminum samples were analyzed at baseline and on days 1, 4, 8, and 14.Measurements and Main ResultsIn both the sucralfate and ranitidine groups, clinical characteristics, number of days the patients were on CVVH support (median, 5.5 [range, 2–32] days, and median, 3 [range, 2–18] days, respectively) and duration of prophylaxis (median, 12 [range, 4–42] days, and median, 16 [range, 3–62] days, respectively) were similar. There were no significant differences in the baseline aluminum concentrations (median, 0.37 [range, 0.15–1.63] &mgr;mol/L, vs. median, 0.32 [range, 0.11–1.0] &mgr;mol/L;p= .79). On initiation of therapy, aluminum levels in the sucralfate group increased dramatically on day 1 (median, 0.87 [range, 0.26–4.4] &mgr;mol/L) and peaked on day 4 (median, 2.84 [range, 1.52–4.44] &mgr;mol/L) with seven of the ten patients exhibiting levels of >2 &mgr;mol/L. In the ranitidine group, there were no significant elevations in aluminum levels above baseline. Analysis of the two groups at the four time points revealed that aluminum levels in the sucralfate group were up to 14 times higher, with the confidence intervals suggesting that the true value may be 2–27 times higher (p< .0001). On cessation of CVVH, a rapid decline in aluminum levels was observed. No clinical manifestations of these potentially toxic levels were observed.ConclusionsThe use of sucralfate for stress ulcer prophylaxis in patients requiring CVVH results in toxic elevations in plasma aluminum levels. Alternative agents should be considered for prophylaxis in these patients.