[The metabolic syndrome: a concept in evolution].

The concept metabolic syndrome intends to incorporate in a single disorder all biologic consequences of insulin resistance and associated conditions. The objective of this paper was to discuss strengths and limitations of current definitions of the metabolic syndrome, its epidemiology, and its association with non-alcoholic steatohepatitis (NASH). Definitions proposed by the World Health Organization (WHO) and the National Cholesterol Education Program (NCEP) are specific but possess low sensitivity for detecting insulin resistance. Cut-off points used in these definitions should be "but are not" adjusted for ethnicity; as a result, in non-Caucasian subjects there is lack of agreement among these. For example, in a Mexican population-based survey prevalence was 13.61% using the WHO definition and 26.6% employing NCEP-III criteria. Cases identified with WHO criteria have a more severe form of the disease. NASH is the most common cause of abnormal levels of serum aminotransferases. It shares some aspects of its pathophysiology with the metabolic syndrome and its prevalence is higher among cases with metabolic syndrome compared to with general population. NASH appears to be the hepatic manifestation of the metabolic syndrome.