Trauma, protein losses

One obvious symptom of a patient suffering from trauma is loss of body weight. This is due to increased mobilisation of both triacylglycerol in adipose tissue and degradation of protein in skeletal muscle. 

Androgens and anabolic steroids have been used in conjunction with dietary measures and exercises in an attempt to reverse protein loss after trauma, surgery, or prolonged immobilization and in patients with debilitating diseases. 

Catabolic States. Androgens can be administered for their anabolic properties in conditions where there is substantial muscle catabolism and protein loss.101 Such conditions include chronic infections, severe traumas, severe burns, and recovery from extensive surgeries.35,115 However, the use of androgens in these situations is somewhat controversial. These agents are not typically used as a primary treatment, but as adjuncts to more conventional treatments such as dietary supplementation and exercise. 

This protein loss is mediated by the hormone cortisol, which is secreted in response to stress, and the cytokines that are secreted in response to trauma four mechanisms are involved ... 

Table 9.4 Protein losses (g) over 10 days after trauma or infection...

There Is a Loss of Body Protein in Response to Trauma Infection... 

The presence of proteins in the diet is essential for health. An important question, therefore, is what is the minimal amount of protein that must be provided to maintain health It is not an easy question to answer. Even when no protein or amino acid is consumed, in an otherwise adequate diet, urea is lost from the body due to body protein break down. The daily loss of protein is about 0.34 g per kg or about 24 g protein each day for a 70 kg person (i.e. when no protein is consumed). However, this amount does not represent the minimal intake required, since other factors, (such as the amount of energy consumed, other components in the diet, and trauma physical activity can affect this amount.) The recommended dietary allowance (RDA) for a young adult is 0.8 g per kg per day (Table 8.6). 

Loss of muscle protein in trauma is caused by increased degradation rather than decreased synthesis. The degradation is controlled by changes in the levels of glucocorticoids, insulin and the proinflammatory cytokines TNFa and IL-1. The proteolytic enzyme complex that degrades the protein is the proteasome (Chapter 8). The mechanism by which the enzyme is activated is not known, but increased activities of the enzymes involved in ubiquitina-tion of proteins and an increase concentration of ubiquitin may play a role (Chapter 8). 

Severe bum trauma causes an elevation of semm catecholamines and triggers a hypermetabolic response that is mediated by P-ARs (61-63). This hypermeta-bolic response causes protein catabolism, muscle wasting, and the loss of lean body mass and can persist up to 9 mo after the injury in some patients. Propranolol is one of several drugs that have been used to treat the hypermetabolic... 

Immediately after an injury, there is loss of fluid to extravascular tissue with a resulting decrease in plasma volume. If the decrease is enough to impair circulation, glomerular filtration is diminished. Diminished renal function leads to the accumulation of urea and other end products of protein metabolism in the circulation. In burned patients, serum total protein concentration falls by as much as 0.8g/dL became of both loss to extravascular spaces and catabolism of protein. Serum aj-, tt2-, and y-globulin concentrations increase, but not enough to compensate for the reduced albumin concentration. The plasma fibrinogen concentration responds dramatically to trauma and may double in 2 to 8 days after surgery. The concentration of C-reactive protein rises at the same time. 

Daily protein requirements are based on age, nutrition status, disease state, and clinical condition. The RDA for protein for children is shown in Table 135-10, and for individuals over 18 years of age the RDA is 0.8 g/kg per day, which is much less than most people typically consume. In adults older than 60 years of age, protein needs are increased to 1 g/kg per day to help reduce the loss of LBM that occurs with aging, and up to 1.5 to 2 g/kg per day may be needed in states of metabolic stress such as infection, trauma, and surgery. 

One of the characteristics of critical illness is hypermetabolism. Trauma, burn injury, and sepsis are aU catalysts for the release of mediators that initiate and regulate the hypermetabohc response. The metabolic consequences of this response include altered carbohydrate metabolism, increased protein synthesis and degradation, and increased lipid oxidation, which ultimately result in loss of protein and lean body mass." In a previously well-nourished individual, critical illness can result in the onset of kwashiorkor-like malnutrition within 5 to 7 days. In a previously malnourished individual, critical illness can precipitate severe mixed marasmus-kwashiorkor in 3 to 5 days. In a prospective study of 129 patients admitted to the intensive care unit (ICU), 43% were malnourished." The malnourished patients had an increased length of stay in the ICU (a mean of 27 vs. 19 days) and a statistically significantly increased incidence of complications (55% vs. 40%) compared with well-nourished patients with a similar severity of illness. 

It has been suggested that blood lost into the area of trauma maybe the source of the nitrogen lost (Dll), but the fact that the increased urinary nitrogen loss disappears at highish environmental temperature and also on a protein-free diet argues against this view, and further the introduction of blood of equivalent nitrogen content to that excreted in the urine over and above that which would have been normal on the diets used, did not lead to this scale of loss (C5, C27, M19). 

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