Total parenteral nutrition solution increases bile lithogenicity in rat

The effect of parenteral and enteral nutrition on bile composition was studied in rats. Bile flow, bile fractional composition, bile component output, and lithogenic index were determined in five groups of rats: (A) preoperative control, (B) freely feeding rats infused with normal saline, (C) parenterally fed rats with balanced total parenteral nutrition (TPN) formula (4% amino acids, 22.5% dextrose, 1% Intralipid), (D) constantly intragastrically fed rats with the same TPN formula, and (E) rats fed intragastrically with the same TPN formula but only during 10 hr at night. After 12 days of infusion, bile and blood were collected. There were no differences between the two parenterally and enterally continuously fed groups. Both Groups C and D showed decreased bile flow, decreased bile components output, increased molar percentage concentrations of biliary cholesterol (2.2 ± 0.3 and 1.8 ± 0.1 in Groups C and D, respectively, control, 1.4 ± 0.1), and increased lithogenic index. The cyclically enterally fed group had a normal lithogenic index in the postabsorptive period. Plasma cholesterol and triglycerides were higher in the formula fed groups. There were no changes in plasma liver function tests between the groups. We conclude, therefore, that continuous administration of TPN solution induces an increase in lithogenicity of the bile, independent of the route of administration.