Both high and low plasma glutamine levels predict mortality in critically ill patients.

Purpose: Plasma amino acids are important indicators for understanding human kinetics and amino acid dynamics. We aimed to investigate the association between the plasma glutamine levels and the mortality rates and determine whether plasma glutamine can predict the prognosis of critically ill patients.

Methods: The clinical records of adult patients who were admitted to an ICU were retrospectively evaluated to investigate the plasma levels of amino acids, including glutamine.

Results: Two hundred fourteen patients were included in this study (male, 62%; median age, 64 years; range 20-97 years). The patients' diagnoses included sepsis (45%), trauma (14%), cardiovascular disease (9%), fulminant hepatitis (9%), burns (4%), and others (19%). The mortality rates in patients with plasma glutamine <400 nmol/mL (group L; 39%, 28/71) or ≥700 nmol/mL (group H; 50%, 15/30) were significantly higher (p < 0.05 and p < 0.01, respectively) than those in patients with plasma glutamine levels of 400-700 nmol/mL (group M; 21%, 24/113). Among patients with sepsis, the mortality rates of group L (46%) and group H (67%) were significantly higher (p < 0.05 or p < 0.01, respectively) in comparison with group M (26%).

Conclusion: Both lower and higher plasma glutamine levels were risk factors for mortality in critically ill patients.