Nonalcoholic fatty liver disease: a manifestation of the metabolic syndrome.

Nonalcoholic fatty liver disease (NAFLD) has become the most common form of liver disease, affecting 20% to 30% of the US population. Its clinical manifestations are usually absent or subtle, and it usually comes to medical attention incidentally when aminotransferase levels are found to be elevated or a radiographic study reveals that the liver is fatty. Primary NAFLD is now considered the hepatic manifestation of the metabolic syndrome. The pathogenesis is thought to be a multiple-hit process involving insulin resistance, oxidative stress, apoptosis, and adipokines. In general, the prognosis for simple steatosis is very good; however, nonalcoholic steatohepatitis (NASH) can progress to cirrhosis and hepatocellular carcinoma in 10% to 15% of patients. There is no established treatment for NAFLD except for weight loss and treating each component of the metabolic syndrome.