Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is defined by the pathologic accumulation of fat in more than 5% of hepatocytes in the absence of significant alcohol consumption (daily intake < 20 g in women and < 30 g in men) and by excluding secondary causes of hepatic steatosis. NAFLD can be categorized into two principal phenotypes: nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). NAFL is defined by the presence of macrovesicular steatosis without inflammation, whereas NASH sees inflammation and hepatocyte ballooning injury, is associated with varying degrees of fibrosis, and can progress to cirrhosis and end-stage liver disease. This review addresses the epidemiology, etiology, pathophysiology, diagnosis, treatment, and prognosis of NAFLD. Figures show the spectrum of fatty liver disease, hepatic consequences of insulin resistance, role of liver biopsy in evaluation of NAFLD, histologic features of NASH, and principles of NAFLD. Tables list risk factors and clinical manifestations for NAFLD, physical examination findings in NAFLD, comparison of imaging modalities, and noninvasive fibrosis markers. This review contains 6 figures, 5 tables and 166 references Key words: Nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, non-invasive assessment, vibration controlled transient elastography, magnetic resonance elastography, diet and lifestyle treatment