We aimed to investigate the predictive power of plasma prolidase activity and oxidative-stress parameters for distinguishing in patients with various causes of non-traumatic abdominal pain who presented to the emergency department.

This study enrolled 100 consecutive adult patients and 100 age- and sex-matched healthy controls. The patients were divided into surgically treated patients (STP); medically treated patients (MTP) and nonspecific abdominal pain (NSAP) patients. As predictors of early oxidative changes, the plasma prolidase activity, total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were assessed using a novel automated method.

No significant difference was observed between the patients and the controls with respect to age or sex (p = 0.837 and 0.188, respectively). The plasma TOS, OSI value, and prolidase activity were significantly higher in the patients with abdominal pain than in the controls (p < 0.001, p = 0.001, and p < 0.001, respectively); however, there was no significant difference in the TAS (p = 0.211). The mean plasma TOS, OSI value, and prolidase activity differed significantly among the three groups (p < 0.001, p = 0.001, and p < 0.001, respectively). The STP had the highest TOS and prolidase activity. However, there was no significant difference in the mean plasma TAS in either group of patients (p = 0.419).

The plasma prolidase activity and TOS level, as biomarkers of oxidative stress, enable discrimination of patients with NSAP from those with surgical abdominal pain that requires emergent surgical treatment.