Laboratory diagnostics of non-alcoholic fatty liver disease

Owing to the high prevalence and associated complications of liver fibrosis, of any etiology, and nonalcoholic fatty liver disease (NAFLD), both have become important public health issues. Liver biopsy is considered the gold standard for diagnosis and staging of liver fibrosis, as well as NAFLD. Recent studies have discovered and validated several non-invasive biochemical biomarkers and imaging procedures for the diagnostics of liver fibrosis and NAFLD. In comparison to patented tests (FibroTest ® , Fibrometer ® , and Hepascore ® ), non-patented tests (APRI, ELFG, FIB-4, Forns Index, and MP3) tend to have a lower diagnostic performance, especially for the diagnosis of significant fibrosis (METAVIR stage F2). The difference in performance is less pronounced for the diagnosis of cirrhosis (METAVIR stage F4). Elastography is superior to biomarkers in the diagnosis of cirrhosis (F4) but not fibrosis (F2). However, in 20% of patients elastography cannot be performed or evaluated due to anatomical reasons. Cytokeratin 18 (CK-18) is the most promising single biomarker for the diagnosis of non-alcoholic steatohepatitis (NASH). Scores and algorithms have been less extensively validated for their diagnostic performance in diagnosing and staging of NAFLD and NASH as compared with fibrosis in chronic hepatitis. Data are promising. Patented scores as well as CK-18 appear slightly superior to freely available scores including the NAFLD fibrosis score, which is recommended by American guidelines. In conclusion, non-invasive biomarkers and elastography appear promising as prescreening tools to limit the number of liver biopsies.