1. Operative Research Unit of Osteo-Metabolic and Thyroid Diseases, Fondazione Policlinico Universitario Campus Bio-Medico , Via Álvaro del Portillo, 200, 00128 Rome , Italy
2. Research Unit of Endocrinology and Diabetes, Campus Bio-Medico University of Rome , Via Álvaro del Portillo, 21, 00128 Rome , Italy
3. Research Institute, California Pacific Medical Center , San Francisco, CA 94107 , USA
4. Department of Medicine, University of California, San Francisco , San Francisco, CA 94143 , USA
5. Department of Epidemiology and Biostatistics, University of California, San Francisco , San Francisco, CA 94158 , USA
6. Division of Endocrinology, Diabetes and Clinical Nutrition, School of Medicine, Oregon Health & Science University , Portland, OR 97239 , USA
7. Department of Epidemiology, School of Public Health, University of Pittsburgh , Pittsburgh, PA 15261 , USA