Minor catabolism, e.g. Major catabolism, e.g. major uncomplicated surgery, surgery, trauma, sepsis, mild fever, exercise burns, adult respiratory distress syndrome

Several surveys have shown that many patients in hospital are malnourished. This may be as a result of chronic illness where a marasmus-like picture is seen; alternatively, it may be as a result of severe protein-energy malnutrition as seen in patients in intensive care who are in a state of major catabolism (Table 81.4). During critical illness, cellular demand for some non-essential amino acids (e.g. arginine, glutamine, cysteine) may exceed the body’s synthetic capabilities; in this case the amino acid becomes ‘conditionally essential’. No current parenteral amino acid formulation contains glutamine because of problems with stability. Some formulations lack cysteine.