1. Endocrine Unit; Massachusetts General Hospital; Boston MA USA
2. Department of Clinical Chemistry; University of Helsinki and Helsinki University Central Hospital, Hospital District of Helsinki and Uusimaa, Laboratory Services (HUSLAB); Helsinki Finland
3. Department of Pathology; Massachusetts General Hospital; Boston MA USA
4. Division of Endocrinology; Stanford University School of Medicine; Stanford CA USA
5. Metabolic Diseases Branch; National Institute of Diabetes and Digestive and Kidney Diseases; Bethesda MD USA