The liver is the major site for (1) the synthesis of serum proteins, such as albumin and coagulation factors; (2) urea synthesis for nitrogen metabolism and ammonia clearance; (3) glucose production for maintaining euglycemia; and (4) lipid metabolism including the generation of lipoproteins and ketone bodies. The metabolic functions of the liver consume approximately 20% of resting energy requirements, although the liver constitutes only 2% of body weight. Patients who have significant liver disease demonstrate impaired hepatic metabolic function as well as extrahepatic alterations in glucose (hypoglycemia is most likely in infants, but insulin resistance and impaired glucose tolerance also occur, particularly in older children), lipid (increased lipolytic rates), and protein (decreased protein synthesis and increased amino acid oxidation rates) metabolism.

Nutritional support of an infant or child with liver disease is dependent on the type of liver disease. Needs vary depending on whether the disease is acute or chronic, the degree of cholestasis and hepatic dysfunction, and the age of the patient. These categories are useful for developing nutritional protocols but may overlap; a careful assessment of each child is necessary to understand the factors that increase nutritional risk. This chapter focuses on the nutritional support of the child with chronic liver disease with hepatic impairment or cirrhosis. The common causes of such disease in childhood include drug-induced hepatitis, chronic viral hepatitis, metabolic liver disease, nonalcoholic fatty liver disease, biliary atresia, and autoimmune hepatitis, although many other diagnoses are possible. Acute liver disease, such as acute viral hepatitis or drug-induced liver disease, may cause vomiting and diarrhea and may result in weight loss. Chronic malnutrition, however, is uncommon. Because these acute diseases are brief, they may require no special nutritional therapy unless encephalopathy ensues. Various inborn errors of metabolism that cause liver disease (ie, galactosemia, tyrosinemia, hereditary fructose intolerance, Wilson disease) have specific nutritional requirements and dietary restrictions. The disease-specific diets of these children are generally managed by the hepatologist or metabolic physician, but if the disease progresses to hepatic insufficiency or cirrhosis, the principles described in this chapter apply. Note that children may have chronic liver disease, such as chronic hepatitis B infection, without impairment of hepatic function; these forms of liver disease generally do not impair nutrition.

Advanced chronic liver disease commonly causes protein-energy malnutrition for several reasons, including poor intake, abnormal nutrient metabolism, and maldigestion or malabsorption of nutrients. Poor intake may be attributable to primary disease and comorbidities. Anorexia, nausea or vomiting, delayed gastric emptying, abdominal distention (with presence of ascites and organomegaly), and fluid restriction can all lead to poor intake. Even more, comorbidities such as dysgeusia (eg, impaired taste due to zinc deficiency), poor dentition, depression, encephalopathy, and dietary modification in the setting of renal impairment (eg, hepatorenal syndrome) can all contribute. Cessation in feeding for the purpose of procedures, delay in reinitiation of feeding postprocedure, unnecessary protein restriction, and medication side effects also result in poor intake. Increased energy expenditure, insulin resistance, abnormal growth hormone signaling, abnormal oxidation of macronutrients, and limited glycogen stores increase the risk for malnutrition in these patients.¹ Malabsorption of fat and fat-soluble vitamins frequently complicate childhood chronic cholestatic liver disease. Fat and fat-soluble vitamins require a critical concentration of intraluminal bile acids for micellar solubilization. Cholestasis, with diminished bile flow, results in reduced biliary secretion of bile acids and consequent fat and fat-soluble vitamin malabsorption. Supplementation with the fat-soluble vitamins A, D, E, and K is required to avoid potential deficiencies of these vitamins. Cirrhosis and portal hypertension may also exacerbate malnutrition, with increased protein oxidation and malabsorption secondary to increased mesenteric venous system pressure and villous atrophy. Some liver diseases may be associated with extrahepatic organ dysfunction, such as pancreatic insufficiency (eg, cystic fibrosis), inflammatory bowel disease (primary sclerosing cholangitis), or kidney failure (eg, polycystic kidney disease associated with congenital hepatic fibrosis), which may aggravate the malabsorption or increase nutritional needs, increasing the risk of malnutrition.

Recognizing and managing the nutritional challenges of chronic liver disease improves childhood growth and development and allows the child to lead as normal a life as possible. Children with chronic liver disease and severely compromised hepatic function may eventually be considered for liver transplantation with the ability to effect a long-term cure of the primary disease.² The success of pediatric liver transplantation is optimized in the child with appropriate pretransplant nutritional support.³