1. Department of Endocrinology, University Medical Center, University of Groningen, Hanzeplein 1, 9700 RB, Groningen, The Netherlands
2. Isala, Department of Internal Medicine, Zwolle, The Netherlands
3. 5th Medical Department, Universitätsklinikum Mannheim, Mannheim, Germany
4. Department of Endocrinology, University of Groningen, University Medical Center, Groningen, The Netherlands
5. Department of Pathology and Medical Biology, University of Groningen, University Medical Center, Groningen, The Netherlands
6. Department of Internal Medicine, University of Groningen, University Medical Center, Groningen, The Netherlands