[1] Spanish Society of Laboratory Medicine, Extra-analytical Quality Commission, Barcelona, Spain
[2] Area Laboratory, A Coruña University Hospital Complex, A Coruña, Spain
[3] Department of Laboratory Medicine, Son Espases University Hospital, Palma, Balearic Islands, Spain
[4] Department of Clinical Analysis and Biochemistry, Laboratori Clínic Metropolitana Nord, Germans Trias i Pujol Hospital, Badalona, Spain
[5] Preanalytic Area, Department of Clinical Biochemistry, Vall d’Hebron Hospital, Barcelona, Spain
[6] Clinical Laboratories Corporate Coordination, Catalan Health Institute, Barcelona, Spain
[7] Department of Laboratory Medicine, Arnau de Vilanova University Hospital, IRBLleida, Lleida, Spain
[8] Department of Laboratory Medicine, University of Navarra Clinic, Madrid, Spain
[9] External Quality Assurance Programmes, Spanish Society of Laboratory Medicine, Barcelona, Spain
[10] Department of Laboratory, Cruces University Hospital, Barakaldo, Bizkaia, Spain
[11] Department of Biochemistry, ‘Lozano Blesa’ University Clinical Hospital, Zaragoza, Spain
[12] Department of Laboratory Medicine, La Paz-Cantoblanco-Carlos III University Hospital, Madrid, Spain
[13] Department manager of Preanalytical and Extraanalytical Quality phase, Catlab, Viladecavalls, Barcelona, Spain
[14] Department of Laboratory Medicine, La Paz-Cantoblanco-Carlos III University Hospital, Madrid, Spain.