Plasma Glutamine Levels in Relation to Intensive Care Unit Patient Outcome

Abstract

Low and high plasma glutamine levels are associated with increased mortality. This study aimed to measure glutamine levels in critically ill patients admitted to the intensive care unit (ICU), correlate the glutamine values with clinical outcomes, and identify proxy indicators of abnormal glutamine levels. Patients were enrolled from three ICUs in South Africa, provided they met the inclusion criteria. Clinical and biochemical data were collected. Plasma glutamine was categorized as low (<420 µmol/L), normal (420-700 µmol/L), or high (>700 µmol/L). Three hundred and thirty patients (median age 46.8 years, 56.4% male) were enrolled (median APACHE II score) 18.0 and SOFA) score 7.0). On admission, 58.5% had low (median 299.5 µmol/L) and 14.2% high (median 898.9 µmol/L) plasma glutamine levels. Patients with a diagnosis of polytrauma and sepsis on ICU admission presented with the lowest, and those with liver failure had the highest glutamine levels. Admission low plasma glutamine was associated with higher APACHE II scores (p = 0.003), SOFA scores (p = 0.003), C-reactive protein (CRP) values (p < 0.001), serum urea (p = 0.008), and serum creatinine (p = 0.023) and lower serum albumin (p < 0.001). Low plasma glutamine was also associated with requiring mechanical ventilation and receiving nutritional support. However, it was not significantly associated with length of stay or mortality. ROC curve analysis revealed a CRP threshold value of 87.9 mg/L to be indicative of low plasma glutamine levels (area under the curve (AUC) 0.7, p < 0.001). Fifty-nine percent of ICU patients had low plasma glutamine on admission, with significant differences found between diagnostic groupings. Markers of infection and disease severity were significant indicators of low plasma glutamine.

An analysis of urine and serum amino acids in critically ill patients upon admission by means of targeted LC–MS/MS: a preliminary study

“…This finding is supported by the literature, as low Gln concentrations upon admission to the ICU have previously been reported to be correlated with mortality 35 – 37 . In this study, in contrast to the study of Blauuw et al 38 , only the serum (but not the urine) Gln concentration was significantly higher in non-survivors compared to survivors. Interestingly, the incidence of septic shock was not associated with changes in either the urine or serum concentrations of Gln.…”

“…Interestingly, the incidence of septic shock was not associated with changes in either the urine or serum concentrations of Gln. Blaauw et al 38 stated that both low and high values of the serum Gln concentration are associated with increased mortality, as changes in the Gln concentration may be U-shaped. Likewise, according to Tsujimoto et al 39 , both lower and higher values of the serum Gln concentration were reported to be associated with a risk of mortality among patients with sepsis.…”

Immunological Effects of Glutamine Supplementation in Polytrauma Patients in Intensive Care Unit.

“…This study showed a similar mortality and length of ICU stay in both polytrauma groups. However, contradictory findings have been recently reported in the literature regarding the linking between low or high GLN levels and mortality, so the debate is still open (22).…”

Plasma glutamine status at intensive care unit admission: an independent risk factor for mortality in critical illness

“…The low glutamine associated with a high mortality may just be a biomarker without any mechanistic connection. Only a few publications include hyperglutaminemic ICU patients [ 9 – 11 , 14 – 16 ]. A higher than normal plasma glutamine concentration is also reported to be associated with unfavourable outcomes, both at admission and during the course of critical illness [ 9 , 11 ].…”