Yanuo Zhou,1,2,* Yewen Shi,1,2,* Simin Zhu,1,2,* Zine Cao,3 Yushan Xie,1,2 Chendi Lu,1,2 Xiaoxin Niu,1,2 Lina Ma,1,2 Zitong Wang,1,2 Yonglong Su,1,2 Zihan Xia,1,2 Yuqi Yuan,1,2 Jiayi Yang,1,2 Rui Lu,1,2 Yani Feng,1,2 Xiaoyong Ren,1,2 Wei Hou1,2 

1Department of Otorhinolaryngology-Head and Neck Surgery, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China; 2Shaanxi Provincial Key Laboratory for Precision Diagnosis and Treatment of Otorhinolaryngology, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China; 3Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Children Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Xiaoyong Ren, Department of Otorhinolaryngology-Head and Neck Surgery, The Second Affiliated Hospital of Xi’an Jiaotong University, NO. 157 Xi Wu Road, Xi’an, Shaanxi Province, People’s Republic of China, Email cor_renxiaoyong@126.com Wei Hou, Department of Otorhinolaryngology-Head and Neck Surgery, The Second Affiliated Hospital of Xi’an Jiaotong University, NO. 157 Xi Wu Road, Xi’an, Shaanxi Province, People’s Republic of China, Email hw716@163.com

Purpose: This study aimed to explore thyroid function changes in patients with obstructive sleep apnea (OSA) and analyze the relationships among the sleep apnea-specific hypoxic burden (SASHB), the sleep breathing impairment index (SBII), and the function during different sleep stages.
Methods: This retrospective study included 452 patients with OSA who visited the Second Affiliated Hospital of Xi’an Jiaotong University between August 2017 and March 2024. The severity of OSA was evaluated, grouping patients by their apnea–hypopnea index (AHI), SASHB, SBII, and both SASHB and SBII during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. Multiple linear regression analyzed the independent relationships between the AHI, SASHB, SBII, and thyroid function indicators while adjusting for potential confounders.
Results: Significant intergroup differences were observed in thyroid function indicators under various grouping methods, with different trends. After adjusting for confounding factors, SASHB, SASHB during NREM sleep (NREM-SASHB), SASHB during REM sleep (REM-SASHB), SBII, SBII during NREM sleep (NREM-SBII), and SBII during REM sleep (REM-SBII) were independently associated with elevated serum free triiodothyronine (FT3) levels (p < 0.05). Similar results were noted in the male patients, whereas no significant associations were observed in the female patients.
Conclusion: There is an association between OSA and thyroid function, with SASHB and SBII independently linked to elevated FT3 levels across different sleep stages and sex subgroups. Future research should further explore these mechanisms to optimize clinical management and treatment strategies for patients with OSA.

Keywords: obstructive sleep apnea, sleep apnea-specific hypoxic burden, sleep breathing impairment index, thyroid function