1. Department of Propaedeutics of Internal Diseases, Medical Faculty, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
2. Hemodialysis Unit, University Hospital “Kaspela”, 4000 Plovdiv, Bulgaria
3. Second Department of Internal Diseases, Section “Nephrology”, Medical Faculty, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
4. Nephrology Clinic, University Hospital “Kaspela”, 4000 Plovdiv, Bulgaria
5. Second Department of Internal Diseases, Section “Gastroenterology”, Medical Faculty, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
6. Gastroenterology Clinic, University Hospital “Kaspela”, 4000 Plovdiv, Bulgaria
7. Department of Medical Biochemistry, Faculty of Pharmacy, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria