Metabolic changes in human liver associated with preoperative intravenous nutrition

1. This study examined the influence of pre-operative intravenous nutrition upon carbohydrate stores, glucose metabolism and protein synthesis in the liver of patients undergoing laparotomy. 2. Thirty patients with gastrointestinal cancer and weight loss (greater than 5 kg in 3 months) were randomized to receive a hospital diet only or a hospital diet plus intravenous nutrition (0.18 g of N + 125 kJ day-1 kg-1) for 3 or 7 days before laparotomy. Patients who had not lost weight received the hospital diet only and formed a control group. 3. Wedge biopsies of liver were obtained at laparotomy and analysed for glycogen concentration, the activity of three key enzymes of glucose metabolism, 6-phosphofructokinase (EC 2.7.1.11), fructose bisphosphatase (EC 3.1.3.11) and hexokinase (EC 2.7.1.1), and the capacity for protein synthesis. 4. Compared with controls and the hospital diet group, both phosphofructokinase and fructose bisphosphatase activity were reduced in patients who received intravenous nutrition, suggesting the utilization of glucose for glycogen synthesis with a reduction in the glycolytic flux. Consistent with these changes, patients who received intravenous nutrition had a significantly higher glycogen concentration compared with the control and hospital diet groups. 5. Maximal rates of protein synthesis were achieved after only 3 days of intravenous nutrition. 6. The provision of intravenous nutrition was associated with changes in hepatic metabolism suggestive of repletion of energy stores and a higher capacity for protein synthesis.