Abstract
Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD), is the most common liver disease. It has a rapidly growing patient population owing to the increasing prevalence of obesity and type 2 diabetes. Patients with MASLD are primarily treated by family physicians when fibrosis is absent or mild and by gastroenterologists/hepatologists when fibrosis is more advanced. It is imperative that a system for the appropriate treatment and surveillance of hepatocellular carcinoma be established in order to ensure that highly fibrotic cases are not overlooked among the large number of MASLD patients. Family physicians should check for viral hepatitis, autoimmune hepatitis, alcoholic liver disease, and drug-induced liver disease, and should evaluate fibrosis using NIT; gastroenterologists/hepatologists should perform liver biopsy, ultrasound elastography (260 units in Japan as of October 2023), and MR elastography (35 units in Japan as of October 2023). This review presents the latest findings in MASLD and the role, accuracy, and clinical use of NIT. It also describes the collaboration between Japanese primary care and gastroenterologists/hepatologists in Japan in the treatment of liver diseases, including MASLD.