Department of Endocrinology, USHATE "Acad. Iv. Penchev", Faculty of Medicine, Medical University-Sofia, Sofia, Bulgaria. Institute of Pathophysiology "Ljubodrag Buba Mihailović", Faculty of Medicine, University of Belgrade, Belgrade, Serbia. Institute of Medicinal Physiology "Richard Burian", Faculty of Medicine, University of Belgrade, Belgrade, Serbia. Department of Endocrinology, CHC Bežanijska kosa, Faculty of Medicine, University of Belgrade, Belgrade, Serbia. Endocrine Unit, Metropolitan Hospital, Athens, Greece. Division of Endocrinology and Metabolism, Department of Internal Medicine, Hacettepe University School of Medicine, Ankara, Turkey. Clinic for Endocrinology, Diabetes and Metabolic Diseases, University Clinical Centre of Serbia, Faculty of Medicine, University of Belgrade, Dr Subotića 13, 11000 Belgrade, Serbia. Electronic address: djmacut@gmail.com.