Energy intake can determine albumin synthesis in man after surgery

Albumin synthesis rate, nitrogen balance, plasma hormone levels, and selected substrates were measured after operation in 12 patients who underwent colonic operations who were randomized to receive an intravenous fluid regimen that contained either 3.5% amino acids with 20% fat and 2.5% glucose or 3.5% amino acids with 20% fat alone. The albumin synthesis rate was higher in patients who received the first of these intravenous mixtures (357 +/- 34 mg/kg/day versus 216 +/- 22 mg/kg/day; p less than 0.01), but they also had a significantly higher intake of calories (10.2 +/- 1.1 calorie/kg/day versus 6.4 +/- 0.6 calorie/kg/day; p = 0.01). The mean albumin synthesis rate in the group who received amino acids with glucose and fat is the highest we have measured in our series of studies. Although a previous trial in a similar group of patients suggested that glucose acts on albumin synthesis by diverting uptake of amino acids into skeletal muscle, it is possible that the impressive increase in the albumin synthesis rate in patients of the present series who received supplementary glucose is related to the extra energy infused. In contrast, nitrogen balance was similar in both groups, and thus was not predictive of protein synthesis. In addition, myofibrillar protein degradation appears to be equivalent in the two groups, as indicated by 3-methylhistidine output. Plasma albumin synthesis thus may be sensitive, especially to energy intake.