Oxidative stress markers in tears of patients with Graves' orbitopathy and their correlation with clinical activity score.

BACKGROUND

To investigate the concentrations of oxidative stress markers, 8-hydroxy-2'-deoxyquanosine (8-OHdG) and malondialdehyde (MDA), in tears and their correlation with the clinical activity score (CAS) in patients with Graves' orbitopathy (GO) according to disease activity.

METHODS

We recruited 27 participants with inactive stage GO, 35 participants with active stage GO, and 25 healthy controls without GO. The tear concentrations of 8-OHdG and MDA were determined by enzyme-linked immunosorbent assay. The correlation between CAS and the concentrations of tear 8-OHdG and MDA were analyzed according to the disease activity in the GO patients.

RESULTS

The levels of 8-OHdG and MDA were 56.30 ± 16.81 ng/mL and 5.39 ± 1.31 pmol/mg, respectively, in the control subjects, and 123.46 ± 22.67 ng/mL and 13.59 ± 3.93 pmol/mg, respectively, in patients with inactive stage GO, and 215.14 ± 35.61 ng/mL and 22.52 ± 4.63 pmol/mg, in patients with active stage GO. The mean concentrations of 8-OHdG and MDA were higher in patients with inactive and active stage GO compared with the control group (all P < 0.001). Furthermore, in the active stage group, tear concentrations of 8-OHdG and MDA were higher than those in the inactive stage group (all P < 0.001). The level of 8-OHdG (r = 0.676, P < 0.001) and MDA (r = 0.506, P = 0.002) correlated with CAS in the active stage GO group.

CONCLUSIONS

The concentrations of 8-OHdG and MDA in tears increased in patients with GO, especially in those in the active stage. In patients with active stage GO, CAS correlated significantly with the tear 8-OHdG and MDA levels.