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Nonalcoholic Fatty Liver Disease: Overview and Risk Factors

Nonalcoholic fatty liver disease (NAFLD) comprises a spectrum of conditions characterized by hepatic fat accumulation in the absence of alcohol abuse, with fat making up at least 10% of the liver tissue (steatosis). Nonalcoholic steatohepatitis (NASH), in which fat accumulation is accompanied by inflammation, is the most common type of NAFLD and the most common form of liver disease in the United States.1 Clinically, NASH may be indistinguishable from alcoholic hepatitis, but it is most often a subclinical disease.

The progressive accumulation of triglycerides in hepatic tissue results from increased delivery of fatty acids to the liver, decreased export of fatty acids from the liver, or impaired oxidation of fatty acids within the liver. Insulin resistance is thought to play a key role in disease development by causing alterations in lipid metabolism, leading to increased uptake of fatty acids by the liver and increased oxidation of lipids within it.

Most patients remain asymptomatic, although nonspecific symptoms, such as fatigue, malaise, and tenderness of the upper–right abdomen may occur. In more serious cases, the pathologic features resemble those of alcoholic liver disease, and may include fibrosis, inflammation, necrosis, and cirrhosis.

Risk Factors

    • States of insulin resistance (typically related to obesity, diabetes mellitus, and metabolic syndrome).
    • Hyperlipidemia, especially hypertriglyceridemia.
    • Severe or rapid weight loss.
    • Total parenteral nutrition.
    • Drugs (eg, amiodarone, tetracycline, glucocorticoids, synthetic estrogens, and certain pesticides).
    • Pregnancy. Rarely, fatty liver occurs during pregnancy.
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    Nonalcoholic Fatty Liver Disease: Diagnosis and Treatment >>