[1] Med Univ Sofia, Univ Hosp Alexandrovska, Dept Internal Med, Clin Endocrinol & Metab Dis, 1 Georgi Sofiiski St, Sofia 1431, Bulgaria
[2] Univ Hosp Lozenetz, Dept Clin Immunol, Eliezer Papo St, Sofia 1407, Bulgaria
[3] Univ Hosp St Anna, Emergency Dept, 1 Dimitar Mollov Str, Sofia 1709, Bulgaria
[4] Med Univ Sofia, Dept Internal Med, Clin Gastroenterol, Univ Hosp St Ivan Rilski, 15 Acad Ivan Evst Geshov, Sofia 1431, Bulgaria