1. Department of Internal Medicine, Medical Center Leeuwarden, AD Leeuwarden, Netherlands
2. Department of Endocrinology, University Medical Center Groningen, RB Groningen, Netherlands
3. Department of Clinical Chemistry, Rijnstate Hospital, TA Arnhem, Netherlands
4. Department of Surgery, Medical Center Leeuwarden, AD Leeuwarden, Netherlands
5. Department of Surgery, Rijnstate Hospital, TA Arnhem, Netherlands
6. Department of Internal Medicine, Rijnstate Hospital, TA Arnhem, Netherlands