BACKGROUND:Nitric oxide (NO) is an important signal molecule in many types of cells and tissues. Efficiently balanced NO production was noted to play an important role in the healing of burns. However, the exact pathophysiological role of NO in burns and its potent relation with clinical and laboratory parameters has not been elucidated. METHODS:A cohort of 23 burn patients followed for 5 days were enrolled. NO, antioxidant capacity (AC), NO synthase (NOS) activity and xanthine oxidase (XO) activity were indirectly determined by fluorophotometer. Multiple regression against total burn surface area (TBSA), age, weight, height, proximity of septic episode, hemoglobin, white blood cells, percent of neutrophils, platelets, glucose, urea, potassium, sodium and albumin was performed. RESULTS:Elevation of NO, XO and AC levels is observed from day 2 (p<0.00001), day 4 (p=0.005) and day 6 (p=0.036), respectively. At the end of follow-up period (day 6), NO production was found to independently correlate with TBSA, glucose levels and percent of neutrophils (p=0.0004), AC with age, hemoglobin and glucose levels (p=0.012), and NOS with proximity of septic episode and glucose levels (p=0.027). CONCLUSIONS:NO production exerts its prophylactic effect from the first 24h after burn, and is independently correlated with severe injury, enhanced neutrophil motivation and augmented glucose levels, thus possibly representing a response to stress. This need might trigger induction of XO and salvage of antioxidants, as suggested by their rise at a later stage. These data underline that an effort to compromise stress and to administer antioxidants could be a priority in the treatment of these patients.