Glutamine as a Supplement to Parenteral Nutrition

Vaneck VW, Matarese LE, Robinson M, Sacks GS, Young LS, Kochevar M. A.S.P.E.N. position paper: parenteral nutrition glutamine supplementation. Nutr Clin Pract. 2011;26:479-494.

The A.S.P.E.N. Novel Nutrient Task Force examined the utility of glutamine in addition to parenteral nutrition (PN) for the hospitalized patient. Glutamine is the most common amino acid in the blood. During critical illness, the body becomes unable to produce enough glutamine to meet required needs.

Glutamine can be compounded into a PN solution as a free amino acid. However, because of its relative instability in this form, it must be added daily to the PN formulation. This requires a PN compounding center that has the resources and processes to complete this compounding with a physician’s order. Alternatively, glutamine dipeptides (L-alanyl L-glutamine and glycyl L-glutamine) are available in many locations outside of the U.S. These dipeptides are water- and heat-stable and have a shelf life of up to two years. When injected parenterally, these dipeptides are hydrolyzed to L-glutamine rapidly by peptidase, which is present in the vascular endothelium.

Using a PubMed search, the Task Force identified papers addressing parenteral glutamine. The recommendations of the Task Force were based on meta-analysis papers, published clinical guidelines, review articles, and a review of selected original articles when there was a discrepancy. Seventeen meta-analysis papers were found; seven were excluded for various reasons.

The Task Force determined that parenteral glutamine administration is associated with a decrease in infectious complications, a decrease in hospital length of stay, and possibly a decrease in mortality in critically ill, post-operative, or ventilator-dependent patients requiring PN. The heterogeneity of the populations in the studies, however, called for additional research to confirm the recommendations. The Task Force additionally pointed out that there may be a utility in positive blood culture reduction in bone marrow transplant patients with the use of parenteral glutamine. (There is not enough data to make recommendations in pediatric patients.) A dose of >.2 g/kg/day is suggested. There is no data to suggest that parenteral glutamine is harmful.