Investigation of Protein Metabolism with Respect to Amino Acid Administration

Abstract

A comparative study of the protein metabolism of two groups of patients having suffered major trauma (group I, n = 26, and group II, n = 16) and of two groups having undergone major surgery (group III, n = 10, and group IV, n = 9) was performed from the 2nd to the 11th day of treatment. All of the patients received approximately 35 kcal/kg body weight/day. In addition the patients in groups I and III received a 10% amino acid solution containing 0.24 g N/kg body weight/ day whereas groups II and IV were administered a 5% solution containing only essential and semiessential amino acids amounting to 0,12 g N/kg body weight/day. The 24-hr nitrogen output in urine, the serum free amino acid concentration as well as the serum protein fractions of transferrin and the C₃c and C₄ complements were contrasted. Significant differences between traumatised patients and those having had major surgery with respect to nitrogen balance and serum free amino acid concentrations were observed regardless of the pattern of nutrition. However, only slight differences in the concentrations of serum protein fractions of the two groups of patients were noted. Following amino acid solution the polytraumatised patients exhibited an average N balance of —11.9 g N/day, which is indicative of a severely catabolic metabolism. The average nitrogen loss observed in the postsurgical patients amounted to only half this amount. Following administration of the semiessential amino acid solution an appreciable difference in the nitrogen balance between comparable groups was not observed. However, the blood urea nitrogen was lower. In both the postoperative as well as the traumatized patients glycine, alanine, and proline levels were reduced to below normal. Thus, in the treatment of the catabolic patient with adequate renal function, a routine parenteral nutrition consisting of essential and semiessential amino acids exclusively can not be considered advantageous. (Journal of Parenteral and Enteral Nutrition 9:725-731, 1985)