1. Department of Nephrology, Oslo University Hospital Ullevål, Oslo, Norway;
2. Oslo Centre for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway;
3. Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway;
4. Institute of Clinical Medicine, University of Oslo, Oslo, Norway;
5. Department of Haematology, Oslo University Hospital and Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway