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Evidence of liver disease in children may take different forms.
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 abdominal vessels
that extend from the upper abdomen to the chest and hemorrhoids
seen with portal hypertension, palmar erythema (eFig.
419.1), spider nevi (eFig. 419.2) digital
clubbing, isolated splenomegaly and excoriations of the skin due
to pruritus. An evaluation and management of nutritional deficiencies
due to liver disease, pruritus, variceal bleeding and ascites are
further discussed in Chapter 425.
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Laboratory studies may help confirm the presence of liver injury
in the absence of other obvious clinical findings. Thus, “screening” laboratories
in patients with non-specific symptoms may reveal elevations in
liver-related enzymes, or liver functions in the absence of clinically
apparent liver disease, being the only sign of liver injury.
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The evaluation of the various presentations of liver disease
depends upon the specific abnormalities identified and the severity
of illness. Patient age must also be considered because the likelihood
of various disorders varies with age. This chapter first reviews
the diagnostic tests utilized for evaluation of the infant and child
with liver disease, then discusses the approach to diagnosis of
infants and children with various presentations of liver disease.
The management of chronic liver disease is further discussed in Chapter 425. Details of the diagnostic approach
for various liver infections are discussed in Chapters 247 and 308; and for liver tumors in Chapter 427.
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Although commonly referred to as “liver function tests,” the
majority of serum tests measure the enzymes that are produced within
the hepatocytes or biliary system but are not measures of physiologic function.
The serum levels of these enzymes that include a serum aspartate
aminotransferase (AST, SGOT), alanine aminotransferase (ALT, SGPT),
gammaglutamyl transpeptidase (GGT), serum alkaline phosphatase (SAP),
and a fractionated bilirubin are nonspecific and can be increased
in numerous different pathologic processes.1 However,
elevation of these tests requires an evaluation for hepatocellular
or bile duct injury. As described below, other common laboratory
tests are more useful for the evaluation of “liver function,” including
measures of serum albumin, ammonia, bile acids, and coagulation
studies.
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Serum Aminotransferase
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Serum aminotransferase elevation is usually caused by hepatocellular injury
owing to inflammation, ...