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Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease from asymptomatic steatosis, with or without elevated aminotransferases, to cirrhosis with relative complications and hepatocellular carcinoma.1 The histological appearance ranges from simple steatosis to hepatocellular damage coupled with inflammation (ie, non-alcoholic steatohepatitis (NASH)) and/or fibrosis.2 The emergence of NAFLD and NASH as clinically relevant entities has parallelled the increasing attention on the metabolic syndrome associated or not with obesity and the central role of insulin resistance, known for a long time to be related to chronic liver disease. However, clinicopathological studies in patients with NASH, as well as recent treatment trials with insulin-sensitising agents, have confirmed that insulin resistance is a cause, not a result, of liver disease.3–6
Epidemiology, socioeconomic and demographic factors
Paediatric NAFLD has become the most frequent chronic liver disease in children and adolescents in industrialised countries due to the growing prevalence of childhood obesity and overweight (figure 1).7 9 NAFLD affects from 2.6% to 9.8% of children and adolescents, and this figure increases up to 74% among obese individuals.9–12 The disease is also significantly associated with type 2 diabetes mellitus and all features of the metabolic syndrome (MetS).8 12 13 A recent survey on adolescent participants in the National Health and Nutrition Examination Survey (NHANES) 1999–2004 found elevated alanine aminotransferase (ALT) in 8% of US adolescents aged 12–19 years. However, this survey is based only on the abnormality of ALT values and, since ALT is not a precise indicator for the presence of NAFLD, the true prevalence could be significantly higher.14 In a case series of autopsies performed on children 2–19 years of age at the time of death, the prevalence of histologically proven NAFLD was 9.6%.1 A more precise estimate of the prevalence of NAFLD and NASH can be obtained by evaluating obese …
Footnotes
Competing interests None.
Provenance and peer review Commissioned; externally peer reviewed.