1 Section of Gastroenterology, Department of Medicine, Levanger Hospital, Kirkegata 2, 7600, Levanger, Norway. ingunn.sagberg@gmail.com.
2 Section of Gastroenterology, Department of Medicine, Levanger Hospital, Kirkegata 2, 7600, Levanger, Norway.
3 Department of Pathology and Medical Genetics, St. Olavs Hospital, Trondheim, Norway.
4 Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.