Evaluation of Serum Vitamin D Levels in Obstructive Sleep Apnea Syndrome

Objective: The relationship between obstructive sleep apnea syndrome (OSAS) and vitamin D deficiency (VDD) has been an attractive issue for researchers in recent years because both are prevalent conditions with common comorbidities and pathophysiological mechanisms. However, the reported results have often been inconsistent, possibly due to multiple confounders such as obesity. The aim of this study was to assess serum 25-hydroxyvitamin D [25(OH)D] levels in cases screened for OSAS and demonstrate whether there is an association between [25(OH)D] and OSAS.Materials and Methods: Two hundred and sixty two cases were retrospectively analyzed. The ones with an apnea hypopnea index (AHI) of =5/hour were categorized as OSAS patients, and <5/hour were classified as non-OSAS controls. Clinical features, polysomnographic indices, and serum 25(OH)D levels were compared between the groups.Results: Serum 25(OH)D levels were similar between OSAS patients and non-OSAS controls as well as among different disease stages within the OSAS group itself. OSAS patients were then divided into two groups regarding the presence of VDD (<20 ng/mL). Although no difference was detected in terms of AHI, body mass index (BMI) was significantly increased in the VDD group (p=0.04). An inverse correlation was observed between 25(OH)D and BMI (p=0.037) in OSAS patients.Conclusion: The current study demonstrated that neither the presence nor severity of OSAS has a significant association with serum 25(OH)D levels. Our results also confirmed the well-known negative correlation between increased BMI and vitamin D.