Liver dysfunction and parenteral nutritional therapies

Protective effect of parenteral glutamine supplementation on hepatic function in very low birth weight infants

BACKGROUND & AIMS

Hepatic dysfunction is one of the most frequent complications of parenteral nutrition. Very low birth weight (VLBW) infants are more sensitive to liver injury due to physiological immaturity. Our studies in animals showed that glutamine supplementation could attenuate TPN-associated liver injury. The aim of study was to investigate whether parenteral glutamine supplementation can improve hepatic tolerance in VLBW infants.

METHODS

We performed a double-blind, randomized, and controlled clinical study to investigate whether parenteral glutamine supplementation can improve hepatic tolerance in VLBW infants. Thirty VLBW infants at two children's centers were randomly assigned to either a control group or a glutamine-supplemented group. The primary endpoints were hepatic function and mortality. The secondary endpoints were the time to achieve full enteral nutrition, episodes of gastric residuals, duration of parenteral nutrition, weight and head circumference gain, length of hospitalization, and days on ventilator.

RESULTS

The serum levels of aspartate aminotransferase (AST) and total bilirubin (Tbi) were decreased after PN in the glutamine-supplemented group (P < 0.05). No deaths occurred in this study. Four infants assigned to the control group and two infants in the glutamine-supplemented group were withdrawn from the study, according to intention to treat: relative risk [RR]: 1.182; 95% confidence interval [CI]: 0.937-1.490.

CONCLUSIONS

Parenteral glutamine supplementation can improve hepatic tolerance in very low birth weight infant, suggesting a hepato-protective effect.

Parenteral nutrition related hepato-biliary disease in adults

Parenteral nutrition is a life-saving therapy in patients with intestinal failure. One of the major causes of morbidity and mortality in patients receiving long-term total parenteral nutrition (TPN) is liver disease. Early on, there is steatosis, which can evolve to steatohepatitis and eventually to cholestasis of varying severity. The etiology of parenteral nutrition related liver disease is multifactorial. Provision of excess calories in the TPN solution, along with lipids administered >1 g/kg are thought to increase the risk of parenteral nutrition related liver disease. Other factors such as nutrient deficiencies and nutrient toxicities may also play a role in the pathogenesis of liver disease, along with sepsis and the lack of enteral stimulation. Non-pharmacological management strategies for TPN-related liver disease include enteral stimulation, optimal TPN composition, and avoidance of excess carbohydrate and lipid calories. Pharmacological therapy with ursodeoxycholic acid and antibiotic therapy to reduce the risk of bacterial translocation and sepsis should be considered. Early referral for transplantation should be considered in patients with evidence of portal hypertension. This review focuses on the clinical aspects, pathogenesis, and management strategies of parenteral nutrition-related liver disease in adult patients.

Glutamine attenuates TPN-associated liver injury in infant rabbits

The aim of this study was to assess the effects of parenteral alanyl-glutamine dipeptide (Ala-Gln) on TPN-associated liver injury. Forty-three New Zealand rabbits (6-8 days old) were divided into three groups: 12 in the control group (maternal fed); 18 in the TPN group (TPN for 10 days); 13 in the Gln-PN group (TPN+Ala-Gln 400 mg kg(-1) day(-1) for 10 days). At the end of the experiment, liver function and histology were evaluated; MDA content of liver tissues and hepatocyte apoptosis by TUNEL assay were also determined. The serum concentration of direct bilirubin and bile acid in the Gln-PN group was significantly lower than TPN group (P < 0.05), but showed no difference compared with the control group. AST level of the Gln-PN group was lower than the other two groups. The light microscopy (LM) features in the TPN group included cholestasis or diffuse steatosis, while in the Gln-PN group, inflammatory infiltration and mild hydropic degenerative changes were mainly found without obvious cholestasis or proliferation of bile ducts. The electron microscopy appearances corresponded with LM findings. The liver MDA content in the Gln-PN group was clearly lower than the TPN group (P < 0.05), and was lower without statistical significance compared with control group. TUNEL assays showed the ratio of apoptotic hepatocytes in the TPN group was the highest among all the groups (44.59 +/- 6.68 vs. 0.92 +/- 0.85 in the control group, P < 0.01; 44.59 +/- 6.68 vs. 4.14 +/- 2.76 in the Gln-PN group, P < 0.01). There were significantly fewer apoptotic hepatocytes in the Gln-PN group. From this study, we found that glutamine dipeptide supplementation could attenuate TPN-associated liver injury in infant rabbits, and could also decrease liver MDA production and hepatocyte apoptosis during total parenteral nutrition.