Glutamine and its metabolite
glutamate serve as the main energy substrates for immune cells, and their plasma levels drop during severe illness. Therefore,
glutamine supplementation in the
critical care setting has been advocated. However, little is known about
glutamine metabolism in severely but not
critically ill medical patients. We investigated the prognostic impact of
glutamine metabolism in a secondary analysis of the Effect of Early
Nutritional Support on
Frailty, Functional Outcomes, and Recovery of Malnourished Medical Inpatients Trial (EFFORT), a randomized controlled trial comparing individualized
nutritional support to usual care in patients at nutritional risk. Among 234 patients with available measurements, low plasma levels of
glutamate were independently associated with 30-day mortality (adjusted HR 2.35 [95% CI 1.18-4.67, p = 0.015]). The impact on mortality remained consistent long-term for up to 5 years. No significant association was found for circulating
glutamine levels and short- or long-term mortality. There was no association of
glutamate nor
glutamine with
malnutrition parameters or with the effectiveness of
nutritional support. This secondary analysis found
glutamate to be independently prognostic among medical inpatients at nutritional risk but poorly associated with the effectiveness of
nutritional support. In contrast to ICU studies, we found no association between
glutamine and clinical outcome.