Association between obstructive sleep apnea and thyroid function: A 10-year retrospective study

To explore whether the obstructive sleep apnea (OSA) has an impact on thyroid function in patients.

The data of 853 patients were retrospectively collected from the Second Affiliated Hospital of Xi'an Jiaotong University in recent ten years. All the objects were divided into the control group, mild-moderate and severe OSA groups according to the result of polysomnography.

In the non-elderly population (age <60), there were significant differences in serum free triiodothyronine (FT3) and total triiodothyronine (TT3) between the mild-moderate and severe OSA groups (all p < 0.05). And there were differences in serum total thyroxine, anti-thyroid peroxidase, and antithyroglobulin between the control and mild-moderate OSA groups (all p < 0.05). Moreover, FT3 was associated with age (OR = 0.98, p < 0.05) and apnea-hypopnea index (OR = 1.01, p < 0.05). The occurrence of thyroid nodules was associated with average transcutaneous oxygen saturation (Mean SaO₂) (OR = 0.97, p < 0.05). In the elderly (age ≥60), there was no difference in FT3 and TT3 between the mild-moderate and severe OSA. While the occurrence of thyroid nodules was also associated with Mean SaO₂ (OR = 0.90, p < 0.05).

In the non-elderly population, the progress of OSA may promote the increase in thyroid hormone (especially FT3) levels, while in the elderly population not. In the whole age population, Mean SaO 2 is associated with the occurrence of thyroid nodules. Future research on the relationship between OSA and thyroid function, and age stratification is necessary.