Serum levels of nitrate, nitrite and advanced oxidation protein products (AOPP) in patients with nonalcoholic fatty liver disease

Oxidative stress is increased and anti-oxidant defense mechanisms are impaired in patients with hepatosteatosis. The aim of the present study was to evaluate the serum levels of several oxidant and anti-oxidant markers in patients with nonalcoholic fatty liver disease (NAFLD). Thirty-four patients with NAFLD, and 19 healthy controls were included. In this study, we measured serum nitrate and advanced oxidation protein product (AOPP) as the oxidizing products and nitrite as the anti-oxidizing marker. Nitrate and nitrite levels were measured using a calorimetric method, and levels of serum AOPP were measured by a spectrophotometric method using a commercial ELISA kit. Serum nitrate and AOPP levels were significantly higher in the NAFLD group compared to the control group. Serum nitrite and N-N levels were similar between the two groups. Serum nitrate and N-N levels were found to be significantly higher in patients with elevated ALT levels compared to patients with normal ALT levels. Serum nitrite and AOPP levels were comparable between these groups. Mean platelet volume (MPV) was significantly lower in the NAFLD group compared to the control group. Serum levels of oxidizing agents including nitrate and AOPP increase in patients with NAFLD. In contrast, serum nitrite, an antioxidant agent, does not adequately increase to compensate for the oxidizing effects in these patients.