1. Section of Nephrology, University Hospital of North Norway, Tromsø, Norway
2. Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway
3. Helgeland Hospital Trust, Sandnessjøen, Norway
4. Department of Nephrology, Oslo University Hospital Ullevål, Oslo, Norway
5. Institute of Clinical Medicine, University of Oslo, Oslo, Norway