Evidence-Based Clinical Practice Guidelines for Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) 2026

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most prevalent chronic liver disease worldwide, with an increasing number of patients progressing to cirrhosis and hepatocellular carcinoma (HCC). Early identification of individuals at high risk for advanced fibrosis is essential for preventing liver-related events and improving long-term outcomes. This guideline summarizes current evidence and provides practical recommendations for the diagnosis, risk stratification, and management of MASLD in clinical practice. These recommendations were developed through systematic evaluation of the literature and expert consensus. Diagnostic approaches, including noninvasive fibrosis assessment tools, imaging, biochemical testing, and indications for referral to gastroenterology/hepatology specialists, were reviewed. Advanced fibrosis is the major determinant of liver-related morbidity and mortality in MASLD. The Fibrosis-4 (FIB-4) index is a widely accessible and reliable first-line noninvasive tool for fibrosis risk stratification. Patients with elevated FIB-4 values or clinical features suggestive of progressive liver injury should undergo secondary assessment with elastography and be referred to a specialist when appropriate. Liver biopsy is not routinely required for the diagnosis of MASLD but remains essential for establishing a definitive diagnosis of at-risk metabolic dysfunction-associated steatohepatitis (MASH), assessing inflammatory activity, resolving discrepancies between noninvasive tests, and differentiating MASLD from other chronic liver diseases. Lifestyle modification remains the foundation of management, with pharmacological therapy considered for patients with a high likelihood of at-risk MASH. MASLD represents a heterogeneous disease spectrum in which advanced fibrosis is the key prognostic factor. These guideline recommendations aim to standardize clinical practice and support evidence-based management of MASLD in Japan.