Whole Body Protein Synthesis in Relation to Basal Energy Expenditure in Healthy Children and in Children Recovering from Burn Injury

Abstract

Summary: Dynamic aspects of whole body nitrogen metabolism in children recovering from burn injury have been examined in relation to basal metabolic rate (BMR). A continuous administration of [¹⁵N]glycine was used to estimate the rates of whole body protein synthesis (S) and breakdown (C) in five acutely burned children (ages 5–16 years) and in nine healthy subjects (ages 9–18 years). S (grams of protein per kg body wt per day) and BMR were significantly correlated (r = +0.73; P < 0.01). There was no significant correlation of C with BMR. The ratio of S (grams of protein per day) to BMR (kilocalories per day) was the same in burned and healthy children; the mean value for all children was 0.10 ± 0.03 g protein synthesis/basal kcal. Calorie intake and S were significantly correlated (r = +0.70; P < 0.01). There were significant correlations between BMR and percentage of total body surface area burned (r = +0.66; P < 0.01), and BMR and age (r = −0.57; P < 0.05). Age did not correlate significantly with percent of total body surface burned.

Speculation: A significant proportion of basal energy expenditure is directly associated with energy needs for whole body protein synthesis and breakdown. The results of the present study demonstrated an increase in BMR in children recovering from burn injury, and the statistical correlations between the rate of S and BMR suggest that body protein synthesis accounts for approximately 50% of the variation in resting energy expenditure in the burned child. If more extensive data on the correlation between rates of S and energy expenditure can be obtained, it should be possible to exploit this relationship to estimate the energy intake required to support a rate of S that would equal or exceed the rate of C and result, therefore, in net tissue protein gain.

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