The first Endo-ERN participant of this exchange program is Savi Shishkov, an endocrinologist in training at the the “St. Marina” University Hospital, and a assistant in the Department of Internal Medicine of the Medical University in Varna, Bulgaria. He was motivated to apply for this fellowship because of his interest in rare endocrine disease, and expanding the international cooperation between ERN HCPs. He has started his exchange to the Leiden University Medical Center under the supervision of Endo-ERN coordinator prof.dr. A.M. Pereira Arias, and pituitary MTG leader prof.dr. N.R. Biermasz on October 5th. During the four-week program, an insight into the tertiary referral center’s outpatient clinic, including the way of shared decision making, treatment, and outcome evaluation will be offered.