Secretoneurin levels in patients with obstructive sleep apnea syndrome

Obstructive Sleep Apnea Syndrome (OSAS) is a sleep-related breathing disorder characterized by frequent micro-awakenings and oxygen desaturations due to restricted airflow in the upper airway. Secretoneurin (SN) is a neuropeptide whose expression increases under hypoxic or ischemic conditions and plays a role in angiogenesis and antiapoptotic processes. Due to secretoneurin being a neuropeptide sensitive to hypoxia, this study investigated the relationship between OSAS and secretoneurin and the performance of secretoneurin in distinguishing OSAS. A total of 120 patients were included in the study. Patient groups were determined based on the apnea-hypopnea index (AHI) values obtained from polysomnography (PSG). Serum SN levels were measured from blood samples taken after PSG. Serum SN levels were compared between groups; the relationship between SN and age, body mass index (BMI), sleep time with SpO2 below 90% during PSG, AHI, and gender was investigated using multiple regression analysis. OSAS was detected in 74.2% of patients (n = 89). SN levels (ng/mL) of the groups were as follows: no OSAS 13.26 ± 6.22; mild 12.16 ± 3.81; moderate 11.6 ± 2.83 and severe 10.91 ± 4.29, and the difference between the groups was not statistically significant (p=0.282). ROC analysis showed that serum SN levels had low discriminatory capability for OSAS (AUC = 0.573; 95% CI 0.436-0.710). For the best cutoff value (18.0045 ng/mL), sensitivity was as 96.63% and specificity was as 29.03%. Furthermore, regression analysis revealed a significant relationship only between age and SN (b = -0.101; p=0.011). In conclusion, our study did not find a significant relationship between serum SN levels and the severity or presence of OSAS. Due to SN's low specificity and limited discriminatory ability, it was concluded that it is not a sufficient biomarker for predicting OSAS in clinical use.