Evidence of liver disease in children will take different forms. Children can present with clinical manifestations of acute or chronic liver disease. Physical findings are the most obvious and include jaundice, hepatomegaly (with or without splenomegaly), and ascites. More subtle physical findings in chronic liver disease include prominent superficial abdominal vessels and hemorrhoids seen with portal hypertension, palmar erythema (Fig. 414-1), spider nevi (Fig. 414-2), digital clubbing, isolated splenomegaly, xanthomas, and excoriations of the skin due to pruritus. Children may also be identified as having liver disease in the absence of obvious physical findings. For example, biochemical tests obtained to assess patients with nonspecific symptoms may reveal abnormalities in liver-related enzymes or liver functions.
Palmar erythema in a patient with liver disease, showing the characteristic blotchy redness. (Reproduced with permission from Wolff K, Goldsmith LA, Katz SI, et al [eds]. Fitzpatrick’s Dermatology in General Medicine. 7th ed. New York: McGraw-Hill; 2008.)
Spider nevi in a patient with cirrhosis. (Reproduced with permission from Wolff K, Goldsmith LA, Katz SI, et al [eds]. Fitzpatrick’s Dermatology in General Medicine. 7th ed. New York: McGraw-Hill; 2008.)
Evaluation of liver disease depends on a number of factors, including liver test abnormalities, severity of clinical and biochemical abnormalities, patient age, and others. This chapter will review the biochemical and functional tests used to evaluate the infant and child with liver disease and outline an approach to the diagnosis of liver disease in infants and children with various clinical presentations.
BIOCHEMICAL EVIDENCE OF HEPATOCELLULAR OR BILE DUCT INJURY
Common biochemical tests used to assess the liver can be divided into 2 broad categories that reflect (1) liver or bile duct cell injury and (2) liver cell function. Although commonly referred to as “liver function tests,” elevation of serum enzymes that are produced within the hepatocytes or biliary system reflect liver or bile duct cell injury and not cell function. The serum levels of these enzymes, which include aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), and serum alkaline phosphatase (SAP), are nonspecific and can be increased in numerous different pathologic processes. However, elevation of these tests often requires an evaluation for hepatocellular or bile duct injury. More apt markers of hepatic function can be divided into (1) markers of synthetic capacity such as prothrombin time, international normalized ratio (INR), albumin, and the coagulation factors V and VII; (2) markers of conjugation and excretory capacity such as bilirubin and bile acids (BAs); and (3) markers of metabolic capacity such as glucose and ammonia.
Serum aminotransferase elevation is usually caused by hepatocellular injury owing to inflammation, toxin, or ...