Association of thiol/disulphide homeostasis with Bethesda classification of thyroid nodules and thyroid cancer

Ultrasonography and fine-needle aspiration biopsy are frequently used to diagnose thyroid cancer. However, supportive data might be required in case of diagnostic difficulty. This study investigated whether there is a relationship between thiol/ disulphide homeostasis and cytological and histopathological diagnosis of thyroid nodules.

The patient group consisted of 81 individuals with euthyroid nodular (single/multiple) goiter scheduled for thyroidectomy, and the control group consisted of 28 age- and sex-matched healthy volunteers who had no thyroid nodule on ultrasonographic evaluation. All participants were selected among the admissions to the study clinic between June 2017 and June 2018, and venous blood samples were collected. The samples of the patients were taken before surgery. Thiol and disulphide levels were analysed with the automated spectrophotometric method.

The mean age of the patient group was 45.66 ± 10.45 years, and the mean age of the control group was 43.53 ± 11.49 years (p = 0.365). The increasing Bethesda categories were positively correlated with the disulphide level (r = 0.281, p = 0.011), disulphide/native thiol ratio (r = 0.241, p = 0.030) and disulphide/total thiol ratio (r = 0.250, p = 0.024). Disulphide/native thiol ratio and disulphide/ total thiol ratio were significantly higher in the histopathologically malignant (euthyroid nodular goiter but final pathology reported malignant) compared to histopathologically benign (euthyroid nodular goiter but final pathology reported benign) (p = 0.012; p = 0.007, respectively) and control groups (p = 0.006; p = 0.004, respectively), but no significant difference was found in these ratios between benign and control group (p = 0.711; p = 0.749, respectively).

Oxidative stress parameters were significantly higher in thyroid cancer. A positive correlation was detected between Bethesda categories with increased risk of malignancy and the disulphide/native thiol ratio and the disulphide/total thiol ratio.