Intravenous fat and glucose in liver cirrhosis

Little is known about lipids recently introduced (with other nutrients) in the parenteral feeding of hepatic encephalopathy, for conflicting results. For this reason 5 cirrhotic patients and 5 healthy controls were infused with 0.8-1.0 g/kg of a commercially available fat emulsion (Intralipid (R) 10%) in combination with 1.6-2.0 g/kg of glucose as 20% intravenous solution during an 8 hr period. Timed blood samples (before and every 4hrs for 24hrs) were obtained for the assay of glucose, insulin, glucagon, free fatty acids (FFA), free and total tryptophan (TRP), the last using a high performance chromatographic method developed in our laboratory. The results confirm a poor glucose tolerance and insulin-resistance in cirrhotic patients, who presented also high base levels of glucagon which normalized during the infusion. The triglycerides were and remained higher in controls but their percent variation resulted greater in patients. From a pathologically augmented basal level (0.73 ± 0.11 VS 0.39 ± 0.12 mVal/l, mean ± SEM), FFA fall progressively during infusion in cirrhotic patients (0.40 ± 0.08), but then rise and remain high in the second half of the study (1.01 ± 0.10), a pattern that is quite different from that seen for the controls. Free TRP is significantly higher in cirrhotic patients (17.7 ± 2.6 vs 11.04 ± 0.8 μmol/l, p<0.01) and remains unchanged throughout the study, as well as the ratio of free to total TRP. The delayed and persistent increase of FFA confirms a reduced clearance of intravenous lipids in cirrhotic patients and accounts for a displacement of TRP from albumin-binding sites. It is concluded that a combined fat and glucose load determines a long-lasting increased availability of TRP to peripheral tissues (brain included) and this might interfere with neurotransmission through an increased serotonin synthesis.