1 University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Groningen, The Netherlands. d.kremer@umcg.nl.
2 Department of Sustainable Health, Campus Fryslân, University of Groningen, Leeuwarden, The Netherlands.
3 Center Obesity Northern Netherlands (CON), Department of Surgery, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
4 University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Groningen, The Netherlands.
5 University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Endocrinology, Groningen, The Netherlands.