1. Laboratory Medicine , IRCCS San Raffaele Scientific Institute , Milan , Italy
2. Department of Medical Biochemistry and Pharmacology , Haukeland University Hospital , Bergen , Norway
3. Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus) , Bergen , Norway
4. School of Medicine , Acibadem Mehmet Ali Aydınlar University , Istanbul , Turkey
5. Hospital Universitario La Paz, Madrid, Spain, and Quality Analytical Commission of Spanish Society of Clinical Chemistry (SEQC) , Madrid , Spain
6. Department of Global Public Health and Primary Care , University of Bergen , Bergen , Norway
7. Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Clinical Pathology Laboratory , Milan , Italy