γ-Glutamyl transferase: a marker of nonalcoholic fatty liver disease in patients with the metabolic syndrome.

OBJECTIVE: The incidence of metabolic syndrome has increased in Mexico and nonalcoholic fatty liver disease (NAFLD) is a common complication. The authors aimed to evaluate the role of hepatic enzymes as biomarkers for NAFLD in patients presenting metabolic syndrome. METHODS: We studied 193 nondiabetic individuals with metabolic syndrome identified from a population-based cross-sectional survey. To identify NAFLD, real-time gray-scale abdominal ultrasound was performed, and the right, left, and caudate hepatic lobules were observed to assess the size, echogenicity, and borders of the liver. All individuals answered a questionnaire for risk factors, and anthropometric measures and blood pressure were obtained. The concentration of hepatic enzymes and insulin in blood was measured and the Homeostatic Model Assessment index was calculated. RESULTS: A total of 160 individuals were identified as presenting NAFLD (82.9%). Body weight, BMI, and the waist-hip ratio increased as a direct result of the presence and severity of fatty liver. A similar situation was observed in the levels of triglyceride and hepatic enzymes aspartate aminotransferase and γ-glutamyltransferase (GGT), basal insulin level, and the Homeostatic Model Assessment index. In a multivariate model, the variables associated with the occurrence of NAFLD were sex, triglyceride and GGT levels, and obesity. CONCLUSION: The main factors that predict the occurrence of NAFLD are levels of triglyceride and GGT in the blood, as well as obesity. The accumulation of fat in the liver, in addition to increased oxidation and oxidative stress at the hepatic level, may be the mechanisms through which these factors increase the risk of NAFLD.

¿Qué es una cohorte? / What is a cohorte?

Las cohortes son estudios epidemiológicos descritivos, que se efectúan en un universo conocido en el cual todos sus miembros comparten una característica, pero que al momento de reunirlos por primera vez, ninguno ha presentado el acontecimiento que interesa estudiar; diferencian a los individuos en grupos de expuestos o no expuestos y requieren una observación detallada durante todo su desarrollo por ser parte de la historia natural de la enfermedad en cuestión. Pueden calificarse como propectivas (concurrentes), retrospectivas (históricas), o bidireccionales de acuerdo con el momento en que sucede la exposición en relación con la observación; existe una modalidad especial conocida como casos y controles incluidos en una cohorte. Sirven para estudiar la relación causa-efecto o hablar de asociaciones confiables, por lo que pueden ser útiles para evaluar el riesgo y el pronóstico