1. Department of Laboratory Medicine, Nordland Hospital Trust, 8092 Bodø, Norway
2. Hepatology Division, Department of Upper GI Diseases, Porphyria Centre Sweden, Karolinska Institute and Karolinska University Hospital, 14186 Stockholm, Sweden
3. Research Laboratory, Nordland Hospital Trust, 8092 Bodø, Norway
4. Department of Nephrology, Nordland Hospital Trust, 8092 Bodø, Norway
5. Department of Clinical Medicine, UiT-The Arctic University of Norway, 9019 Tromsø, Norway
6. Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
7. Harvard Medical School, Boston, MA 02115, USA