Nonalcoholic fatty liver disease (NAFLD)
Nonalcoholic fatty liver disease (NAFLD) is secondary to excessive lipid accumulation in the hepatocytes (i.e., steatosis), where other etiologies including alcoholism have been excluded. NAFLD is rising in incidence at an alarming rate in the United States and is currently thought to affect 20% to 30% of patients in the general population and 85% to 90% of patients undergoing evaluation for weight-reduction surgeries. It is the most common cause of chronic liver disease in the United States. Obesity, diabetes mellitus, and hyperlipidemia are known risk factors. NAFLD has been long considered the hepatic manifestation of metabolic syndrome. Patients with uncomplicated NAFLD are usually asymptomatic, although some patients may have right upper quadrant pain or abnormal liver function tests.
NAFLD represents a spectrum of liver abnormalities from steatosis (i.e., increased liver fat), nonalcoholic steatohepatitis, fibrosis, cirrhosis, and liver failure. Obesity, insulin resistance, hypertension, and dyslipidemia may contribute to the development of NAFLD. Most patients are asymptomatic, but others can present with right upper quadrant pain, hepatomegaly, jaundice, encephalopathy, and other signs of liver disease. Abnormal liver function studies and fatty liver on abdominal ultrasound is diagnostic. Weight loss can reverse pathologic conditions of the liver, and therefore lifestyle modification is the first step in the management of NAFLD. Insulin sensitizer (i.e., metformin and thiazolidinediones) and vitamin E can be considered, but benefits are equivocal.