Non-invasive diagnostic tests for non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a clinico-pathologic spectrum of conditions ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). Although simple or bland steatosis follows a relatively benign clinical course, NASH can potentially progress to cirrhosis (approximately 10 to 15 percent) and hepatocellular carcinoma. NAFLD occurs in an estimated 25 to 30 percent of the US general population, while NASH is reported in 2 to 3 percent of the population. Even though common explanation for the increased prevalence of NAFLD is the increased rate of obesity, the risk of developing NAFLD and NASH is not limited to overweight and obese individuals. Currently, the only way to diagnose NASH or to assess the stage of fibrosis is by obtaining a liver biopsy. Liver biopsy is invasive, expensive, and associated with potential risks, including post biopsy pain, bleeding, organ perforation, and even death; serious complications can occur in 0.3 percent of liver biopsies with 0.01 percent being fatal. This review examines the current strategies for development of the non-invasive techniques that will one day replace liver biopsy and serve as a non-invasive gold standard for the diagnosis and staging of NASH.