1. Department of Internal Medicine I, Division of Endocrinology, University Hospital Frankfurt, Frankfurt am Main, Germany.
2. Department of Endocrinology, Medical Research Center, Polish Academy of Science, Warsaw, Poland.
3. Department of Nuclear Medicine, Medical Center Zajecar, Serbia.
4. Red Cross Blood Transfusion Center, Institute of Transfusion Medicine and Immunohaematology, Frankfurt am Main, Germany.