Metabolic dysfunction associated steatotic liver disease in lean patients. Diagnostic and treatment challenges

Relevance. Metabolic-associated steatotic liver disease (MASLD) became the first pathology among all liver diseases with a tendency for further increase in incidence. Patients with MASLD and normal weight are a special cohort that is difficult to diagnose and treat. The purpose: to analyze the literature about pathogenesis, prognosis of the disease and management of lean patients with MASLD. Materials and methods. The search of the literature devoted to NAFLD or MASLD was conducted in the PubMed and Google Scholar databases, these articles included adult patients with a body mass index of less than 25 kg/m2 for the general population and less than 23 kg/m2 for the Asian population. Discussion. MASLD is observed mainly in individuals with obesity and/or type 2 diabetes mellitus, but 7%-20% of patients with MASLD have a normal weight. This is a specific disease phenotype with a complex pathogenesis including visceral obesity, sarcopenia, genetic polymorphism, altered microbiota profile and behavioral factors. Lean patients with MASLD have a high prevalence of metabolic disorders (arterial hypertension, dyslipidemia, type 2 diabetes mellitus) and increased mortality from cardiovascular diseases, liver diseases and all causes, compared with healthy people. They can develop the same spectrum of liver damage (steatohepatitis, fibrosis, cirrhosis) as individuals with MASLD and obesity. The article describes diagnostic approaches for MASLD in lean people, requiring the exclusion of alternative causes of steatosis, as well as the high risk groups identification. The treatment challenges are the lack of effective pharmacological therapy, the necessity of metabolic factors and lifestyle modification. Conclusion. The obtained data do not allow us to consider MASLD in lean patients as a benign disease. In this cohort, it is necessary to diagnose the stage of liver damage and to screen for cardiometabolic disorders early.