Oxidative DNA damage level and lipid peroxidation status in subclinical hypothyroid patients compared with euthyroid...

This study focused on measuring oxidative DNA damage and oxidative stress biomarkers in subclinical hypothyroidism (SCH) patients to gain insight on the condition's contribution to metabolic consequences. Additionally, it assesses the impact of levothyroxine replacement therapy on oxidative stress and DNA damage in patients with SCH over a specified duration of treatment.

A case-control study was done at the Diabetes and Endocrine Center, Azadi Teaching Hospital, Duhok, Kurdistan Region, Iraq, from June 2024 to February 2025. The participants were divided into four groups: euthyroid controls (G1, n = 80), previously treated SCH (G2, n = 44), newly diagnosed SCH (G3, n = 105), and newly diagnosed SCH patients on follow-up levothyroxine therapy (LT4) (G4, n = 20). Oxidative stress and oxidative DNA damage biomarkers were assessed and compared in all study groups.

The research comprised 249 participants: 169 with SCH and 80 euthyroid controls. Compared to G1, oxidized low-density lipoprotein (ox-LDL) and total oxidant status (TOS) were higher in groups G2, G3, and G4 (p < 0.0001). The marker of oxidative DNA damage 8-hydroxy-2'-deoxyguanosine (8-OHdG) was significantly higher in G3 and G4. The oxidative stress index (OSI) was higher in the SCH groups compared to controls. Total antioxidant status (TAS) was significantly decreased compared to controls (p < 0.0001). There were no significant differences regarding the levels of malondialdehyde (MDA) between the groups.

SCH patients, especially newly diagnosed, show elevated oxidative stress, DNA damage, and reduced antioxidant capacity versus euthyroid controls, elucidating metabolic complications and validating oxidative biomarkers for early risk stratification.