Serum prolidase levels in Graves' disease without ophthalmopathy and its association with oxidative status

The aim of this study was to evaluate serum prolidase levels and its association with oxidative stress in autoimmune thyroid disease (AITD).

25 with Hashimoto thyroiditis (HT) and 25 patients Graves' disease (GD), and 27 healthy controls were enrolled in the study. The patients with signs of Graves' ophthalmopathy were excluded from the study. Serum samples were obtained in euthyroid period at the third month of treatment. Serum prolidase, total antioxidant status (TAS), total oxidative stress (TOS), and total free sulfhydryl (-SH) levels were measured.

Serum prolidase levels were significantly higher in the patients with GD compared to the HT and the healthy control group. Oxidative stress index (OSI) and TOS levels of the patients with both GD and HT were significantly higher compared to those of the control group (p < 0.001, for each), while -SH levels were significantly lower (p < 0.001, for each). There was no significant difference between the patients with HT and healthy control group in terms of prolidase levels (p = 0.580). Prolidase levels were positively correlated with TOS and OSI and negatively correlated with -SH (r = 0.565, p = 0.003; r = 0.604, p = 0.001; r = -0.532, p = 0.006).

Serum prolidase activity is increased in GD patients without signs of ophthalmopathy, and showed a positive correlation with oxidative stress parameters.