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Key Features

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Essentials of Diagnosis
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  • Hepatomegaly in patient with body mass index more than 95th percentile

  • Elevated alanine aminotransferase (ALT) > aspartate aminotransferase (AST)

  • Detection of fatty infiltration of the liver on ultrasound

  • Histologic evidence of fat in the liver

  • Insulin resistance

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General Considerations
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  • A clinicopathologic condition of abnormal hepatic fat deposition in the absence of alcohol

  • Most common cause of abnormal liver function tests in the United States

  • Ranges from bland steatosis, to fat and inflammation, with or without scarring (also referred to as nonalcoholic steatohepatitis, NASH) to cirrhosis

  • Incidence correlates with obesity; in the United States,

    • Up to 10% of all children are affected

    • 38% of obese children are affected

  • Comorbidites include

    • Type 2 diabetes mellitus

    • Hypertension

    • Hyperlipidemia

    • Metabolic syndrome

  • Most children are 11–13 years old at diagnosis

  • Males (ratio of 2:1) and Hispanics at highest risk

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Clinical Findings

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Symptoms and Signs
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  • Most patients are asymptomatic

  • Nonalcoholic fatty liver disease (NAFLD) often discovered on routine screening

  • Some patients may complain of fatigue or right upper quadrant pain

  • Obesity and insulin resistance are known risk factors

  • Moderate sleep apnea is also common

  • Obstructive sleep apnea and hypoxia appear to contribute to disease severity

  • Asymptomatic soft hepatomegaly may be present, but abdominal adiposity may make this difficult to assess

  • Physical findings of insulin resistance (acanthosis nigricans and a buffalo hump) are frequently present

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Differential Diagnosis
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  • Wilson disease

  • Hereditary fructose intolerance

  • Tyrosinemia

  • Hepatitis caused by hepatitis C virus

  • Cystic fibrosis

  • Fatty acid oxidation defects

  • Kwashiorkor

  • Reye syndrome

  • Respiratory chain defects

  • Total parenteral nutrition–associated liver disease

  • Toxic hepatopathy (ethanol and others)

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Diagnosis

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Laboratory Findings
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  • AST and ALT

    • May be normal

    • Do not identify bland steatosis

    • If elevated, typically elevated < 1.5 times the upper limit of normal, with an ALT:AST ratio of > 1

  • Alkaline phosphatase and GGT may be mildly elevated

  • Bilirubin is normal

  • Hyperglycemia and hyperlipidemia are also common

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Imaging
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  • Ultrasonography, CT scan, or MRI can be used to confirm fatty infiltration of the liver

  • While ultrasound costs less and lacks radiation exposure, it may be insensitive in severe central adiposity or if < 30% steatosis is present

  • Radiologic imaging cannot distinguish bland steatosis from the more severe NASH or reliably identify fibrosis

  • Transient elastography is a research tool that shows promise in estimating hepatic fibrosis

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Diagnostic Procedure
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  • Liver biopsy may show

    • Microvesicular or macrovesicular steatosis

    • Hepatocyte ballooning

    • Mallory bodies

    • Lobular or portal inflammation

    • Varying degrees of fibrosis

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Treatment

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  • Lifestyle modifications, through both dietary changes and exercise, to induce slow weight loss

  • A 10% decrease in body weight can significantly improve NAFLD

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Outcome

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Prevention
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  • Weight management

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Complications
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  • Untreated NAFLD with hepatic inflammation can progress ...

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