1. Department of Internal Medicine/Nephrology, Ziekenhuisgroep Twente Hospital, PP Almelo and Hengelo, Netherlands
2. Department of Nephrology, University of Groningen, University Medical Centre Groningen, EZ Groningen, Netherlands
3. Department of Laboratory Medicine, University of Groningen, University Medical Centre Groningen, EZ Groningen, Netherlands
4. Department of Endocrinology, University of Groningen, University Medical Centre Groningen, EZ Groningen, Netherlands