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Epidemiology, clinical features, and diagnosis of nonalcoholic fatty liver disease in adults

Sunil G Sheth, MD
Sanjiv Chopra, MD, MACP
Section Editor
Keith D Lindor, MD
Deputy Editor
Anne C Travis, MD, MSc, FACG, AGAF


Nonalcoholic fatty liver disease (NAFLD) refers to the presence of hepatic steatosis when no other causes for secondary hepatic fat accumulation (eg, heavy alcohol consumption) are present. NAFLD may progress to cirrhosis and is likely an important cause of cryptogenic cirrhosis [1-4].

This topic will review the epidemiology, clinical features, and diagnosis of NAFLD. The pathogenesis, natural history, and treatment of NAFLD are discussed separately. (See "Pathogenesis of nonalcoholic fatty liver disease" and "Natural history and management of nonalcoholic fatty liver disease in adults".)


Patients with nonalcoholic fatty liver disease (NAFLD) have hepatic steatosis, with or without inflammation and fibrosis. In addition, no secondary causes of hepatic steatosis are present. (See 'Differential diagnosis' below.)

NAFLD is subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). In NAFL, hepatic steatosis is present without evidence of significant inflammation, whereas in NASH, hepatic steatosis is associated with hepatic inflammation that may be histologically indistinguishable from alcoholic steatohepatitis [5,6]. Other terms that have been used to describe NASH include pseudoalcoholic hepatitis, alcohol-like hepatitis, fatty liver hepatitis, steatonecrosis, and diabetic hepatitis. (See 'Histologic findings' below and 'NAFLD activity score' below.)


Prevalence — Nonalcoholic fatty liver disease (NAFLD) is seen worldwide and is the most common liver disorder in Western industrialized countries, where the major risk factors for NAFLD, central obesity, type 2 diabetes mellitus, dyslipidemia, and metabolic syndrome are common [7]. In the United States, studies report a prevalence of NAFLD of 10 to 46 percent, with most biopsy-based studies reporting a prevalence of NASH of 3 to 5 percent [8-10]. Worldwide, NAFLD has a reported prevalence of 6 to 35 percent (median 20 percent).


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Literature review current through: Sep 2016. | This topic last updated: Jun 7, 2016.
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