ORIGINAL ARTICLE Investigation of serum bisphenol A, vitamin D, and parathyroid hormone levels in patients with obstructive sleep apnea syndrome Ersin Sukru Erden • Sebahat Genc • Sedat Motor • Ihsan Ustun • Kemal Turker Ulutas • Hatice Kayim Bilgic • Suleyman Oktar • Sana Sungur • Cihangir Erem • Cumali Gokce Received: 9 May 2013 / Accepted: 19 July 2013 / Published online: 1 August 2013 Ó Springer Science+Business Media New York 2013 Abstract Obstructive sleep apnea syndrome (OSAS) is a common health problem, and associated with obesity, metabolic syndrome (MetS), and diabetes. Growing evi- dence shows that 25-hydroxyvitamin-D 3 (25-OH-D) insufficiency and high parathyroid hormone (PTH) levels may be correlated to glucose intolerance, MetS, obesity, and cardiovascular abnormalities similar to OSAS. Bisphenol A (BPA) is an endocrine disruptor agent which exerts a wide variety of metabolic effects. It has estrogenic activity and its exposure may contribute to weight gain, obesity, impaired glucose metabolism, and the develop- ment of diabetes, also similar to OSAS. The aim of this study is to investigate the relationships between OSAS and serum BPA, 25-OH-D, and PTH levels. This study enrolled 128 subjects, with all of the OSAS patients having been diagnosed by polysomnography. The 128 subjects were divided into three groups: a control (n = 43), a moderate OSAS (n = 23) (AHI = 15–30), and a severe OSAS groups (n = 62) (AHI [ 30). The serum BPA, 25-OH-D, and PTH levels for each subject were analyzed. 25-OH-D was lower in both OSAS groups, and PTH was higher in the OSAS groups than in the control subjects. The BPA levels were higher in the severe OSAS group than the moderate OSAS and control. There was a positive corre- lation between the BPA and body mass index, and a neg- ative correlation between the 25-OH-D and BPA levels in all of the individuals. OSAS is related to high BPA and PTH levels, and low vitamin D levels. There is a positive association between BPA levels and OSAS, and the severity of OSAS. These results suggest that the BPA levels may have a role in the pathogenesis of OSAS. E. S. Erden (&) Á S. Genc Á H. K. Bilgic Department of Chest Diseases, Faculty of Medicine, Mustafa Kemal University, 31000 Hatay, Turkey e-mail: dreserden@gmail.com S. Genc e-mail: sebahatakoglu@hotmail.com H. K. Bilgic e-mail: hkayim@hotmail.com S. Motor Á K. T. Ulutas Department of Biochemistry, Faculty of Medicine, Mustafa Kemal University, Hatay, Turkey e-mail: sedatmotor@yahoo.com K. T. Ulutas e-mail: drkemalturker@gmail.com I. Ustun Á C. Gokce Division of Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, Mustafa Kemal University, Hatay, Turkey e-mail: iustun@yahoo.com C. Gokce e-mail: cumaligokce@yahoo.com S. Oktar Department of Pharmacology, Faculty of Medicine, Mustafa Kemal University, Hatay, Turkey e-mail: suleymanoktar@yahoo.com S. Sungur Department of Chemistry, Science and Letters Faculty, Mustafa Kemal University, Hatay, Turkey e-mail: sanasungur@hotmail.com C. Erem Division of Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey e-mail: cihangirerem@hotmail.com 123 Endocrine (2014) 45:311–318 DOI 10.1007/s12020-013-0022-z