1. From the 1Department of Physiology and Biomedical Engineering, Norwegian University of Technology and Science, 2Department of Urology/Surgery, University Hospital of Trondheim, 3Department of Endocrinology/Medicine, University Hospital of Trondheim, Trondheim, Norway, 4Department of Clinical Chemistry, University Hospital, Uppsala, Sweden and 5Department of Gastroenterology/Medicine, University Hospital of Trondheim, Trondheim, Norway