1. Acibadem Mehmet Ali Aydınlar University , School of Medicine, Department of Medical Biochemistry Atasehir , Istanbul , Turkey , Phone: +90 532 744 66 83, Fax: +90 216 576 51 20
2. Research Centre for Metrological Traceability in Laboratory Medicine (CIRME) , University of Milan , Milan , Italy
3. Servizio Medicina di Laboratorio, Ospedale San Raffaele , Milan , Italy
4. Metropolitana Nord Clinical Laboratory (LCMN) , Germans Trias i Pujol University Hospital , Badalona , Spain
5. Department of Medical Biochemistry and Pharmacology, Norwegian Porphyria Centre (NAPOS) , Haukeland University Hospital , Bergen , Norway
6. Norwegian Organization for Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital , Bergen , Norway
7. Department of Laboratory Medicine, La Paz University Hospital , Madrid , Spain
8. Analytical Quality Commission, Spanish Society of Laboratory Medicine (SEQCML) , Barcelona , Spain
9. College of Medicine, Dentistry and Nursing , Dundee University , Dundee, Scotland , UK
10. Certe, Wilhelmina Ziekenhuis Assen , Assen , The Netherlands
11. Institute for Quality Management in Healthcare (IQMH), Centre for Proficiency Testing , Toronto, Ontario , Canada
12. Royo Villanova Hospital , Zaragoza , Spain
13. Quality Healthcare Consulting, Grupo ACMS , Madrid , Spain
14. Department of Clinical Biochemistry , University Hospital of Salamanca , Salamanca , Spain
15. Clinic Laboratory Hospital Vall d’Hebron , Barcelona , Spain
16. Intercomarcal Laboratory Consortiums of Alt Penedès, Anoia and Garraf , Barcelona , Spain
17. Department of Global Health and Primary Care, Faculty of Medicine , University of Bergen , Norway