1. Clinic for Gastroenterohepatology, University Clinical Center of Serbia, 11000 Belgrade, Serbia
2. Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
3. Center of Bone Biology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
4. Special Hospital for Addiction Diseases “Drajzerova”, 11000 Belgrade, Serbia
5. Institute of Medical and Clinical Biochemistry, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
6. Institute for Health Protection of Workers of Serbian Railways, 11000 Belgrade, Serbia
7. Euromedik Hospital, 11000 Belgrade, Serbia