Hígado graso (parte 1): aspectos generales, epidemiología, fisiopatología e historia natural

Fatty liver or NAFLD is defined by the presence of fat or steatosis in hepatocytes and covers a spectrum that goes from simple steatosis, through steatohepatitis (NASH), with inflammation and fibrosis and ending in cirrhosis. It is considered a global world prevalence close to 25% in the general population and is diagnosed between 40 and 50 years, with variations regarding the predominant sex and with ethnic differences, affecting more the Hispanic population. Fatty liver is associated with metabolic syndrome (MS), and obesity is considered the main risk factor for its presence and progression. Fatty liver is a complex and very heterogeneous disorder in its pathophysiology, resulting from the interaction of multiple elements, genetic, epigenetic, environmental, cultural factors, etc. All this together leads to an accumulation of hepatic fat, insulin resistance, hormonal and intestinal microbiota alterations, generating hepatocellular damage through the formation of free oxygen radicals and activation of hepatic fibrogenesis. The natural history of fatty liver is dynamic, patients with simple steatosis have a low risk of progression to cirrhosis, in patients with NASH this risk is increased, however, the process may be reversible, and some people will have spontaneous improvement. Fibrosis seems to be the determinant of overall mortality and outcomes associated with liver disease, it is considered that in all patients fibrosis worsens one stage every 14 years, in NASH it worsens one stage every seven years. Previous studies conclude that approximately 20% of cases of simple steatosis progress to NASH and that approximately 20% of them progress to cirrhosis, with the presence of hepatocellular carcinoma (HCC) in 5 to 10% of them.