Avoiding autocannibalism.

Trauma, sepsis, and surgery increase the catabolic rate.If: hypercatabolism is prolonged the resultant muscle wasting and impaired immune response delay recovery.'The term autocannibalism has been used to describe this self destruc- tive response to illness,2 and a malnourished state, due to increased catabolism, remains a common problem on many hospital wards.In the 1930s Cuthbertson showed that even relatively minor trauma, such as a fractured tibia, was associated with a greatly increased catabolic rate and negative nitrogen balance (indicating net muscle loss).'The breakdown of protein after trauma may have short term advantages-for example, providing amino acids for wound healing and for synthesising acute phase proteins in the liver.Critically ill patients remain in negative nitrogen balance for long periods despite enteral or parenteral nutrition.4Although parenteral nutrition supports protein synthesis, its capacity to do so falls short of the demands of catabolism.Other ways of promoting anabolism and preventing cata- bolism have been proposed.Insulin improves nitrogen bal- ance in patients with trauma, but this effect is short lived.56Growth hormone, with its promotion of lipolysis, muscle synthesis, and the retention of nitrogen, is a logical choice for improving the nutritional state of the critically ill.The recent production of recombinant human growth hormone and its associated peptide insulin-like growth factor 1 has allowed further investigation of these compounds' anabolic potential.Growth hormone has direct actions (lipolysis and insulin antagonism) and direct anabolic actions, which are mediated by insulin-like growth factor 1. Fasting normal subjects and critically ill patients become relatively insensitive to growth hormone, with increased basal concentrations of the hormone associated with low concentrations of insulin-like growth factor 1.78 These observations suggest that the metabolic actions of growth hormone undergo adaptive change during sickness and fasting.9Consequently, the indirect anabolic actions of growth hormone are reduced while the raised basal growth hormone concentrations promote increased lipolysis and insulin antagonism.Such changes might benefit fasting sick patients by providing metabolic fuels but at the cost of switching off protein synthesis.However, in the context of modern intensive care, where nutritional support is available, this could be counterproductive, with adverse effects on wound healing, muscle strength, and recovery.Recent studies with recombinant growth hormone have