Non-alcoholic steatohepatitis is part of a disease spectrum, non-alcoholic fatty liver disease, ranging from simple steatosis to cirrhosis, which is the most frequent cause of abnormal liver tests. There is clinical and epidemiological evidence that non-alcoholic fatty liver disease is the hepatic manifestation of the metabolic syndrome, having in common insulin resistance.
The interest in the metabolic syndrome concept has been questioned. Insulin resistance, oxidative stress, mitochondrial dysfunction, immune deregulation and adipokines seem to be crucial in the pathogenesis of non-alcoholic fatty liver disease. The main treatment continues to rely on lifestyle changes, including weight loss strategies. Bariatric surgery in morbidly obese patients and insulin-sensitizing agents seem to be beneficial.
There is strong evidence of the association of non-alcoholic steatohepatitis with the features of the metabolic syndrome, with its increased cardiovascular risk. Population interventions in order to change lifestyles and diet patterns that constitute risk factors for both situations are urgently needed. There is, however, evidence that in the presence of other risk factors, insulin resistance may be less important. These secondary forms of non-alcoholic steatohepatitis must be recognized, as they are potentially treatable by withdrawing the steatogenic factor.