Controversies in the Diagnosis and Management of NAFLD and NASH.

Nonalcoholic fatty liver disease (NAFLD) is recognized as the most common cause of chronic liver disease in the United States. Nonalcoholic steatohepatitis (NASH) occurs in a subset of patients with NAFLD and is characterized by the presence of hepa-tocellular injury, which is progressive in a substantial proportion of cases and can lead to cirrhosis and all of its complications. Although the diagnosis of NAFLD can be made through imaging studies or liver biopsy, the diagnosis of NASH still requires histologic confirmation. Liver biopsy should be performed in the presence of risk factors for advanced disease. Measures aimed at promoting weight loss, a healthier lifestyle, and optimization of metabolic risk factors remain the cornerstone of management of NAFLD. Therapeutic agents that are presently considered the most promising in NAFLD are effective in less than 50% of patients. Among patients with biopsy-proven NASH, treatment with pharmacologic agents should be considered; however, the role of specific agents in NASH still needs further study. Despite a wealth of research over the past 15 years, many controversies remain with respect to the diagnosis and management of NAFLD and NASH as well as the influence of alcohol on liver disease progression in these patients.