1. Institute of Endocrine and Metabolic Sciences, San Raffaele, Vita‐Salute University and IRCCS Hospital Milan Italy
2. Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases Metabolism and Ageing KU Leuven Leuven Belgium
3. Osteoporosis Clinical Research Program on Aging, University of Wisconsin Madison WI USA
4. Vitamin D Standardization Program LLC Havre de Grace MD USA
5. McGuire Veterans Affairs Medical Center and Virginia Commonwealth University School of Medicine Richmond VA USA
6. Section of Specialized Endocrinology, Department of Endocrinology, Oslo University Hospital, Rikshospitalet, Oslo, Norway, and Faculty of Medicine University of Oslo Oslo Norway
7. Jean Mayer USDA Nutrition Research Center on Aging Tufts University Boston MA USA
8. Department of Medicine, School of Clinical Sciences Monash University Calyton Victoria Australia
9. Department of Medicine Stanford University School of Medicine Stanford CA USA
10. Endocrine Laboratory, Department of Clinical Chemistry Amsterdam UMC, Vrije Universiteit Amsterdam and University of Amsterdam, Amsterdam Gastroenterology & Metabolism Amsterdam The Netherlands
11. Department of Biomedical and Molecular Sciences Queen's University Kingston Ontario Canada
12. Faculty of Medicine Memorial University of Newfoundland St. John's Newfoundland and Labrador Canada
13. Division of Endocrinology Escola Paulista de Medicina–Universidade Federal de Sao Paulo (EPM‐UNIFESP) São Paulo Brazil
14. Department of Internal Medicine, Endocrine Section Amsterdam University Medical Center Amsterdam The Netherlands
15. Department of Clinical and Experimental Medicine University of Pisa Pisa Italy
16. Department of Internal Medicine and Medical Disciplines University of Rome “Sapienza” Rome Italy
17. Unit of Endocrinology and Diabetes Campus Bio‐Medico, University of Rome Rome Italy
18. Division of Bone and Mineral Diseases Washington University in St. Louis St. Louis MO USA
19. Service of Bone Diseases Geneva University Hospitals and Faculty of Medicine Geneva Switzerland
20. School of Population Health University of Auckland Auckland New Zealand
21. Department of Physiology McGill University Montreal Quebec Canada
22. Department of Medicine, Endocrinology Division, College of Physicians and Surgeons Columbia University New York NY USA