Diagnosis of Nonalcoholic Steatohepatitis

The prevalence of non-alcoholic fatty liver disease (NAFLD) has increased in the last years up to 25% in the adult population. This disease includes a large spectrum of disorders, from simple fatty liver disease to cirrhosis and Hepatocellular Carcinoma (HCC), and they are related to chronic metabolic conditions. NAFLD is characterized by the presence of at least 5% of hepatic steatosis without evidence of hepatocellular injury. The diagnosis of this disease should be of exclusion and focused on its progression, treatment, and identification of the prognosis. The European Association for the Study of the Liver (EASL), the National Institute for Health and Care Excellence (NICE), the Italian Association for the Study of the Liver (AISF), and the American Association for the Study of the Liver (AASLD), published their Clinical Guidelines that have identified the criteria for the diagnosis of NAFLD, several, using imaging or histological diagnostic methods, although they imply a different approach and screening. The Fatty Liver Index and the NAFLD Liver Fat Score are used by 3 out of 5 Guidelines and they are easily calculated using blood tests and clinical information. Other non-invasive scales for NAFLD are the NAFLD fibrosis score (NFS), Fib-4, AST/ALT ratio index; also the ELF panel, Fibrometer, Fibrotest, Hepascore; and some imaging techniques that include transient elastography, magnetic resonance elastography (MRE), and shear wave elastography. Finally, proteomic’s and glycomic’s technologic biomarkers are currently under investigation and recent use, such as Cytokeratin 18 and Sirtuin 1. Still, liver biopsy remains the gold standard to distinguish between steatohepatitis and simple steatosis, using the histological classification and staging scoring systems of NAFLD Activity Score (NAS) and the Steatosis Activity Fibrosis (SAF), to evaluate the disease’s activity.