1. Clinical Biochemistry Department , Vall d’Hebron University Hospital , Barcelona , Spain
2. Department of Clinical Chemistry and Laboratory Medicine , Leiden University Medical Centre , Leiden , The Netherlands
3. Department de Bioquímica i Biologia Molecular , Universitat Autònoma de Barcelona , Bellaterra , Spain
4. Department of Clinical Biochemistry , University Hospital of Salamanca , Salamanca , Spain
5. Department of Medical Biochemistry , Uludag University School of Medicine , Bursa , Turkey
6. Diagnost-IQ, Expert Centre for Clinical Chemistry , Purmerend , The Netherlands
7. Laboratori de Referència d’Enzimologia Clínica, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona , Bellaterra , Spain
8. Laboratory for Clinical Chemistry and Hematology, Amphia , Breda , The Netherlands
9. Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek , Nijmegen , The Netherlands