Serum YKL-40 level is correlated with apnea hypopnea index in patients with obstructive sleep apnea syndrome

OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) has been associated with elevated biochemical markers of inflammation. Although the exact mechanism is unknown, both sleep deprivation and hypoxemia are believed to be important causative factors. YKL-40, also known as chitinase-like protein, has been shown to be related to various inflammatory conditions including atherosclerosis, diabetes, cancer and asthma. The present study aimed to evaluate the relationship between YKL-40 levels and the Apnea Hypopnea Index (AHI) in patients with obstructive sleep apnea syndrome. PATIENTS AND METHODS: The study was conducted at the Sleep Unit of the Namik Kemal University Research Center. From January 2013 to December 2013, 120 patients diagnosed with OSAS by polysomnography and 40 subjects without OSAS were recruited. Patients in both groups were matched by age, sex, and body mass index (BM!). They were further divided into groups of mild, moderate and severe OSAS based on their AHI value. Serum YKL-40 concentrations were measured by the enzyme linked immunosorbent assay (ELISA). RESULTS: OSAS patients showed significantly elevated YKL-40 levels compared to the control group; 102,05 (23.14) pg/ml in the control group vs. 144.81 (65.53) pg/ml in the OSAS group. A Spearman correlation analysis showed that serum YKL-40 levels were significantly and positively correlated with AHI (r = 0.434, p < 0.001) and oxygen desaturation index (r = 0.374, p < 0.001). CONCLUSIONS: The study demonstrated that high serum YKL-40 levels correlated with the severity of OSAS and might serve as a nonspecific biomarker for prediction and progression of the disease.