Pinyi Zhou,1,* Hongmei Li,2,* Jingman Qiu,1 Jing Ye,1 Jingyu Guo,1 Yun Yao,1 Hongyan Li,1 Yanfen Shi,1 Yufan Duan,1 Yunhui Lv1 

1Department of Sleep Medicine, The Affiliated Hospital of Kunming University of Science and Technology, The First People’s Hospital of Yunnan Province, Kunming, 650500, People’s Republic of China; 2Department of Neurology, The Affiliated Hospital of Kunming University of Science and Technology, The First People’s Hospital of Yunnan Province, Kunming, 650500, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Pinyi Zhou, Department of Sleep Medicine, The Affiliated Hospital of Kunming University of Science and Technology, The First People’s Hospital of Yunnan Province, Kunming, 650500, People’s Republic of China, Email zpy_study@163.com Yunhui Lv, Department of Sleep Medicine, The Affiliated Hospital of Kunming University of Science and Technology, The First People’s Hospital of Yunnan Province, Kunming, 650500, People’s Republic of China, Email Lyhys99@163.com

Objective: Obstructive sleep apnea-hypopnea syndrome (OSAHS) is closely associated with hypothyroidism. This study aimed to evaluate the prevalence and correlation of hypothyroidism in patients with OSAHS.
Methods: This investigation included a cohort of 1693 patients newly diagnosed with OSAHS, all of whom underwent polysomnography and thyroid function assessments.
Results: The study cohort comprised 1693 OSAHS patients (60.4% male). No significant differences in thyroid-stimulating hormone (TSH) or free thyroxine (FT4) levels were observed across OSAHS severity groups (p = 0.670 and p = 0.307). Notably, patients with overt hypothyroidism demonstrated significantly lower lowest oxygen saturation (LSpO2) levels than their euthyroid counterparts (p = 0.035). The analysis did not reveal any significant correlations between TSH/FT4 levels and the apnea-hypopnea index, mean oxygen saturation (MSpO₂), or LSpO₂. Nevertheless, TSH levels were positively correlated with female sex and age (p = 0.001), while no correlation was found with body mass index. After controlling for sex and age, TSH was positively correlated with apnea-hypopnea index (p = 0.002) and negatively correlated with both MSpO₂ and LSpO₂ (p = 0.001). In contrast, FT4 levels exhibited a negative correlation with apnea-hypopnea index (p = 0.016) and positive correlations with MSpO₂ and LSpO₂ (p = 0.030 and p = 0.018). The overall prevalence rates of hypothyroidism and overt hypothyroidism within the study population were determined to be 13.7% and 3.8%, respectively, with no significant differences observed across the severity categories of OSAHS (p = 0.166 and p = 0.193). Subclinical hypothyroidism was identified in 9.9% of the patients, with a notably lower prevalence in those with severe OSAHS compared to those with milder forms of the condition (p = 0.004).
Conclusion: In patients with OSAHS, 13.7% had hypothyroidism, with 3.8% being overt hypothyroidism and 9.9% being subclinical hypothyroidism. Thyroid function parameters are associated with the severity of OSAHS and are influenced by sex and age.

Keywords: sleep apnea, obstructive, hypothyroidism, prevalence, correlation