Protein-sparing therapy in postoperative patients. Effects of added hypocaloric glucose or lipid

In patients receiving hypocaloric total parenteral nutrition, protein sparing with infusions of amino acids alone is alleged to occur because low insulin levels allow mobilization of endogenous fat. Four groups of patients studied for their first four postoperative days received all their nutrition parenterally as: 150 g per day of glucose, protein (as amino acids, 1 g per kilogram per day) alone, protein plus 50 g per day of soybean-oil emulsion or protein plus 150 g per day of glucose. All groups of patients receiving protein had lesser negative nitrogen balance than patients receiving glucose alone. The addition of glucose to protein did not increase negative nitrogen balance. The protein-sparing effect of amino acids appears to be a function of the infused amino acids alone and is not related to the degree of endogenous fat mobilization.