Glutamine kinetics during intravenous glutamine supplementation in ICU patients on continuous renal replacement therapy

Objective: To investigate glutamine kinetics during continuous renal replacement therapy (CRRT) in multiple organ failure (MOF) patients with and without exogenous intravenous glutamine supplementation. Design and patients: In a pragmatic clinical study 12 patients without urine production receiving CRRT were prospectively randomized in a cross-over design to receive glutamine intravenously for 20 h before placebo or placebo before glutamine on two consecutive days. Alanyl-glutamine or placebo (saline) was infused. Measurements: Plasma glutamine concentration was measured in artery, femoral vein, and filtration fluid. Blood flow across the leg was measured and the efflux of glutamine calculated. The rate of appearance of glutamine was calculated from the plasma decay curve of glutamine concentration on the day of treatment. Results: Glutamine supplementation increased plasma concentrations from 570 +/- 252 to 831 +/- 367 mol(-1). Glutamine losses into the filtration fluids were similar during treatment and control days: 25 +/- 13 vs. 24 +/- 11 mmol 24 h(-1), corresponding to 3.6 +/- 1.9 and 3.5 +/- 1.6 mmol 24 h(-1), respectively. Net glutamine balance across the leg was also similar on treatment and control days:150 +/- 138 and 188 +/- 205 nmol min(-1) 100 ml(-1), respectively. The rate of appearance of glutamine was 54 +/- 17 g 24 h(-1). Conclusion: The loss of glutamine into the ultrafiltrate during CRRT in MOF patients suggests a greater need for exogenous glutamine than in patients without renal failure. The leg efflux and the filtration losses of glutamine were not affected in response to intravenous glutamine supplementation.