1. Standardization Laboratory, Diagnostica e Ricerca San Raffaele S.p.A., via Olgettina 60, 20132 Milan, Italy
2. Chair of Clinical Biochemistry and Clinical Molecular Biology, University of Milan Medical School , Milan , Italy
3. Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Haraldsplass Hospital , Bergen , Norway
4. Blood Sciences, Ninewells Hospital and Medical School Ninewells, Dundee, UK