1. Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital , Bergen , Norway
2. Department of Medical Biochemistry and Pharmacology , Norwegian Porphyria Centre, Haukeland University Hospital , Bergen , Norway
3. Department of Global Public Health and Primary Care , University of Bergen , Bergen , Norway
4. Laboratory Medicine , IRCCS San Raffaele Scientific Institute , Milan , Italy