1. Department of Clinical Chemistry, St. Elisabeth Hospital, PO Box 90151, 5000 LC Tilburg, The Netherlands
2. Department of Pathology, University of Virginia Medical School, Charlottesville, VA
3. Laboratoire de Biologie Polyvalente, Centre Hospitalier Général, Rodez, France
4. Laboratory of Clinical Biochemistry, Haukeland University Hospital, and Division of General Practice, University of Bergen, Bergen, Norway
5. Department of Clinical Chemistry, University of Szeged, Albert Szent-Gyorgyi Medical School, Szeged, Hungary