1. Department of Internal Medicine, Second Propedeutic Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
2. Department of Internal Medicine, Medical School, University of Ioannina, Greece
3. Department of Internal Medicine, Division of Endocrinology, University of Patras, Medical School, Rio Hospital, Patras, Greece
4. Third Department of Medicine, University of Athens, Medical School, Sotiria General Hospital, Athens, Greece
5. Department of Internal Medicine, Medical School, University of Crete, Heraklion, Greece
6. Cardiology Department, Tzanio State Hospital, Piraeus, Greece
7. Department of Clinical Biochemistry, Royal Free Campus, University College London Medical School, University College London, UK