Prevalence of glutamine deficiency in ICU patients: a cross-sectional analytical study

Abstract

BackgroundNot only is glutamine deficiency an independent predictor of mortality in intensive care unit (ICU) patients, but glutamine supplementation is also recommended for its proven outcome benefits. However, recent data suggest that early glutamine supplementation in certain patient groups increase mortality. The aim of this study was to investigate plasma glutamine levels of adult ICU patients in the South African setting and to determine relationships between glutamine levels, gender, diagnostic categories and selected inflammatory markers. The data from this study will be used as baseline measurement to support a large scale study that will be undertaken in the South African ICU population.MethodsThis cross-sectional, analytical study included 60 mixed adult ICU patients within 24 h post ICU admission. Plasma glutamine levels were determined on admission. The relationship between glutamine levels, Interleukin-6 (IL-6) and C-reactive protein (CRP); as well as gender- and diagnosis-related differences in glutamine levels were also investigated. A non-parametric ROC curve was computed to determine the CRP concentration cut-off point above which glutamine becomes deficient.ResultsThe median plasma glutamine level (497 μmol/L) was in the normal range; however, 38.3 % (n = 23) of patients had deficient (<420 μmol/L) and 6.7 % (n = 4) had supra-normal glutamine levels (>930 μmol/L). No significant difference could be detected between glutamine levels and gender or diagnosis categories as a group. When only the medical and surgical categories were compared, the median plasma glutamine level of the medical patients were significantly lower than that of the surgical patients (p = 0.042). Glutamine showed inverse associations with CRP levels (r = −0.44, p < 0.05) and IL-6 concentrations (r = −0.23, p = 0.08). A CRP cut-off value of 95.5 mg/L was determined above which glutamine levels became deficient.ConclusionsAbout a third of patients (38 %) were glutamine deficient on admission to ICU, whereas some presented with supra-normal levels. While glutamine levels correlated inversely with inflammatory markers, and a CRP value of above 95.5 mg/L indicated potential glutamine deficiency, the clinical application of this finding needs further investigation.

Plasma Glutamine Levels in Relation to Intensive Care Unit Patient Outcome

“…The average plasma glutamine level in this study compares well to those reported in the literature of similar patient groups, ranging from an average level of 420-497 µmol/L [15][16][17]21,22]. The average age of the subjects was 47 years, which is similar to another South African study [22], but younger than most other studies, which reported average ages of 59 years [15], 64 years [16], 68 years [21], and 74 years [17]. The majority of subjects had a primary ICU admission diagnosis of A small proportion of subjects (n = 47, 14.2%) fell in the high serum glutamine category on admission.…”

“…Using similar cut-off values to define glutamine deficiency, our results are consistent with some of the highest reported figures. The prevalence of glutamine deficiency in studies from The Netherlands ranged between 65% [23], 55% [21], and 31% [17]; a Swedish study reported 44% deficiency [15]; a study from Japan reported a prevalence of 33% [16] and from South Africa a prevalence of 38% was reported [22].…”

Glutaminemia prognostic significance in critical surgical patients – An analysis of plasma aminogram profile; Significado pronóstico de la glutaminemia en pacientes quirúrgicos críticos - Análisis del perfil del aminograma plasmático

“…Positive correlations between glutaminemia at admission and hepatic SOFA scores at admission and at the third and sixth days were in concordance with the association between liver dysfunction and high plasma glutamine concentrations described in the literature (31). The present findings did not corroborate the inverse correlation between admission glutaminemia and C-reactive protein levels observed by Nienaber A et al (32) in a mixed ICU patients cohort.…”

“…High positive correlations observed between admission glutaminemia and plasma concentrations of alanine and arginine were expected since glutamine and alanine are both depleted in catabolic states (32) and glutamine serves as a precursor for de novo production of arginine through the citrulline-arginine pathway (33,34). A moderate direct correlation was also demonstrat- ed between admission glutaminemia and plasma levels of two essential branched-chain amino acids, leucine and isoleucine.…”

“…A moderate direct correlation was also demonstrat- ed between admission glutaminemia and plasma levels of two essential branched-chain amino acids, leucine and isoleucine. Branched-chain amino acids, especially leucine, stimulate protein synthesis, inhibit proteolysis, and promote glutamine and alanine production; its oxidation in skeletal muscle compensates for the increased energy expenditure and glutamine consumption in catabolic states (32). Decrease of mean glutaminemia levels until the third day and concomitant increase of plasma concentrations of citrulline, arginine, ornithine and, mainly, of glutamic acid may indicate the favoring of two metabolic pathways: synthesis of citrulline (in the enterocyte), precursor of arginine (35,36), and production of energy (through the supply of energetic substrates for gluconeogenesis) (37).…”