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Plasma amino acids in critically ill patients


Stress states, sepsis and trauma markedly increase protein catabolism in skeletal muscle, gut, and connective tissue.

Catabolism is potentiated by a sepsis-induced decrease in amino acid uptake in skeletal muscle. One-third of the total amino acid output from skeletal muscle is glutamine and one-third is alanine.


To demonstrate the concentration of plasma amino acids in critically ill patients.

Materials and methods

A prospective analysis of 41 patients (17 women and 24 men) admitted to a 27-bed ICU from July 2002 to May 2003. Twenty-three amino acids were analysed in each patient up to 24 hours of admission in the ICU. The amino acid assays, using high-pressure liquid chromatography, were performed by laboratory CTN and Pardini.


The average patient age was 73.08 years (43–88 years) and the APACHE II score was 18.37 (11–28). Plasma amino acids were obtained in 41 patients and 23 amino acids were analysed (μmol/l). The total value of plasma amino acids was 4257.475 μmol/l (average). The doses of plasma amino acids were: aspartic acid 75.95, glutamic acid 384.45, alanine 587.1, arginine 84.45, asparagine 78.5, cystine 497.55, phenylalanine 179.2, glycine 497.55, glutamine 413.25, hydroxyproline 58.25, histidine 84.55, isoleucine 90.325, leucine 195.5, lysine 190.05, methionine 48.85, ornithine 118.65, proline 201.5, serine 156.75, taurine 167.25, tyrosine 127.85, threonine 167, tryptophan 51.925, and valine 278.975.


The concentrations of alanine, glutamic acid, aspartic acid, phelalanine and arginine were more elevated than the other amino acids. Glutamine was demonstrated to be decreased, probably, as an essential amino acid in sepsis or catabolic patients, greatly consumed.

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Rodigues, M., Ruzany, F., Salgado, D. et al. Plasma amino acids in critically ill patients. Crit Care 9 (Suppl 2), P99 (2005).

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  • Skeletal Muscle
  • Glutamine
  • Glutamic Acid
  • Taurine
  • Aspartic Acid