RESUMO
BACKGROUND: Pathogenesis of nonalcoholic fatty liver disease (NAFLD) remains incompletely known, and oxidative stress is one of the mechanisms incriminated. The aim of this study was to evaluate the role of liver oxidative stress in NAFLD affecting morbidly obese patients. METHODS: 39 consecutive patients with BMI >40 kg/m2 submitted to Roux-en-Y gastric bypass were enrolled, and wedge liver biopsy was obtained during operation. Oxidative stress was measured by concentration of hydroperoxides (CEOOH) in liver tissue. RESULTS: Female gender was dominant (89.7%) and median age was 43.6 +/- 11.1 years. Histology showed fatty liver in 92.3%, including 43.6% with nonalcoholic steatohepatitis (NASH), 48.7% with isolated steatosis and just 7.7% with normal liver. Liver cirrhosis was present in 11.7% of those with nonalcoholic steatohepatitis. Concentration of CEOOH was increased in the liver of patients with NASH when compared to isolated steatosis and normal liver (0.26+/- 0.17, 0.20+/- 0.01 and 0.14+/- 0.00 nmol/mg protein, respectively) (P < 0.01). Liver biochemical variables were normal in 92.3% of all cases, and no difference between NASH and isolated steatosis could be demonstrated. CONCLUSIONS: 1) Nonalcoholic steatosis, steatohepatitis and cirrhosis were identified in substantial numbers of morbidly obese patients; 2) Concentration of hydroperoxides was increased in steatohepatitis, consistent with a pathogenetic role for oxidative stress in this condition.
