1. University Medical Center Groningen, Division of Nephrology, Department of Internal Medicine, University of Groningen, Groningen, the Netherlands
2. University Medical Center Groningen, Department of Laboratory Medicine, University of Groningen, Groningen, the Netherlands
3. Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, the Netherlands
4. University Medical Center Groningen, Division of Endocrinology, Department of Internal Medicine, University of Groningen, Groningen, the Netherlands