Circulating irisin levels in newly diagnosed obstructive sleep apnea patients

Introduction: Obstructive sleep apnea syndrome (OSAS) is commonly associated with obesity, insulin resistance, metabolic syndrome, hypertension, and coronary artery disease. Irisin is a newly identified myokine and its serum concentration was found to be correlated with cardiac troponin and creatin kinase-MB in acute myocardial infarction patients. Furthermore, irisin levels were positively associated with endothelium-dependent vasodilation in type 2 diabetic patients. Aim: In this study, we aimed to investigate serum irisin level in the newly diagnosed OSAS patients. Materials and Methods: After obtaining ethical approval, 32 OSAS patients were included. All patients gave written informed consent. Diagnosis of OSAS was verified by an overnight polysomnography (PSG) and made by an apnea hypopnea index equal to or higher than 5 . Venous blood samples were collected in the morning between 08.00 – 10.00 after PSG (n=25) or after one-night CPAP treatment (n=7). Serum irisin concentrations were studied by ELISA. Results and Conclusion: Serum irisin concentrations were significantly higher in newly diagnosed OSAS group than in OSAS group after one night of CPAP treatment ( 199.7±42.4 vs 159.7±18.3 ng/mL respectively; p<0.01). These results suggest that increased serum irisin levels can be reduced by CPAP treatment and elevated serum irisin levels may be due to increased respiratory muscle activity and body temperature .